EIJING — Zhang Xiaoli's porcelain skin, rosy cheeks and cover-girl features once made her the constant center of attention. Then she grew up to become her father's daughter, just five feet tall.

"I lost my advantage," Ms. Zhang, a 24-year-old law school graduate, said from a Beijing hospital bed. "It was terrible having a younger sister who was taller than me."

So last September, Ms. Zhang decided to take over where nature left off. She checked herself into a hospital here and a doctor cut her shinbones in two, applied a medieval-looking brace to her legs and taught her how to turn its screws so that metal pins would pull her bones apart nearly a millimeter a day, or around four-hundredths of an inch. Today, Ms. Zhang is three and a half inches taller than she was six months ago, though she can not yet walk.

Hundreds of young Chinese, more women than men, obsessed with stature in this increasingly crowded and competitive society, are stretching themselves to new heights on a latter-day rack developed by a Russian doctor 40 years ago to treat dwarfism and deformed limbs. The often painful Ilizarov procedure, named for its inventor, adds length by allowing new bone to grow in the gap left by the gradually separating ends of broken bone. The procedure is used in the United States, but mainly for therapeutic purposes. Its cosmetic use is far less frequent than in China.

If not done carefully, the risks are high. Bones separated too quickly will not mend or will grow together with tissue too fragile to bear the body's weight. Limbs can end up being different lengths and shanks can grow warped, deforming the knee and ankle joints. Nerves may be damaged.

But in a country where there are tallness requirements for jobs, colleges and even spouses, many young people are willing to take such drastic measures to get ahead.

The Chinese are at least as aware of height as Americans are of hair or skin color. It is one of the first attributes offered or asked about when discussing someone new, particularly a person of the opposite sex. Newspaper classified sections are sprinkled with sought-after heights, expressed in centimeters. Matchmakers and personal advertisements are particularly precise in their prerequisites.

On the lonely-hearts page of one recent issue of The Shanghai Morning Post, a 162-centimeter-tall woman (just under 5-foot-4) was looking for a man who was 170 centimeters (5-foot-7) or taller. A 36-year-old man said he was 176 centimeters tall and wanted to meet a 30-year-old woman who was 163 centimeters.

Given the hordes of qualified applicants that descend on any opportunity here, many institutions find height an easy way to cut down the field. That gives a distinct advantage to northern Chinese, who are on average taller than southerners.

Deng Xiaoping, a southerner who stood just 4-foot-11, would have been out of luck had he come of age in this decade. Many divisions of the army in which he made his mark in the 1930's and 40's now require male recruits to be at least 5-foot-3. Even the government that he once led wants only tall Chinese today in jobs that involve meeting foreigners. China's Foreign Ministry demands that would-be diplomats be at least 5-foot-7 if they are men, 5-foot-3 if they are women.

It is no wonder, then, that height remedies are a huge business in this country. Quacks hawk herbal tonics that promise new growth, or magnetic shoe insoles that are said to stimulate the production of human growth hormone. Some doctors give injections of growth hormone.

"This is a developing country with relatively few opportunities and a huge population," said Xia Hetao, the doctor who performed Ms. Zhang's operation. He spoke during a recent interview in his sleekly appointed offices. "The competitive pressures are enormous."

Dr. Xia charges $6,000 to $7,000 to add up to six inches of height, depending on the patient's ideal proportions. The initial operation, in which he severs the thighbone or shinbone through two small incisions in the skin, takes about an hour and a half. He then attaches his own version of a metal fixation device with pins that pierce the skin and are screwed into the bone above and below the break.

Patients turn white plastic dials on the contraptions four times a day to winch their broken bones apart. It takes 15 days to grow one centimeter, or less than half an inch, of new bone. The patients spend an average of six months in the device and three more in recovery.

On Dr. Xia's ward, a plump 24-year-old man with steel-rimmed glasses and short spiky hair said he had been there since November to add three and a half inches to his original 5 feet 3 inches.

He said he had not told anyone outside his family what he was up to.

"I'll say I took injections," he said sheepishly. "They don't have to know."

After performing more than 700 of the leg-lengthening operations, Dr. Xia said only three of his patients had had any complaints. In one case, a 55-year-old man turned out to be too old to heal properly. In another, a 23-year-old woman grew impatient and increased her height too quickly. In a third case, another 23-year-old woman refused to eat sufficiently because she was afraid of getting fat, and so her bones failed to reattach. He said all three cases were corrected with subsequent treatment.

He conceded, though, that most of the country's dozen or so doctors performing the operation had had more frequent trouble.

Newspapers periodically report cases in which the process has gone awry, leaving young women with their feet turned grotesquely on twisted legs or their weakened bones breaking again and again.

Wang Fulin, 33, is still hobbling around after a failed attempt to add four inches to her five-foot frame two years ago. Her doctor in the central Chinese city of Zhengzhou stopped the procedure after stretching her legs a little more than an inch and then left the legs in a bone-fixing frame for 22 months, saying her new bones were too brittle for her to stand on her own. Today, she still cannot squat and walks on legs "that don't feel like my own." Her right foot is set permanently at the 2 o'clock position.

"All I thought about before was beauty, but now I don't know what will happen to me," Ms. Wang said in a telephone interview from her home.

In Beijing, Ms. Zhang said she heard about the Ilizarov procedure after graduating from law school and decided that the interlude before starting work was the perfect time to reinvent herself. She paid Dr. Xia to add nearly four inches to her legs, but lost her nerve at just over three inches when she began hearing the nightmarish stories of leg-lengthening efforts gone bad.

Lying in bed with her white-bandaged legs propped on a metal riser, a Chinese opera playing loudly on the television in her room, she grimaced while recalling the pain she endured after the operation. But she said her motivation was "a desire for perfection — and for marriage."

Her 5-foot-8 high-school sweetheart broke up with her because she was too short to marry at just over 5 feet. She has not had a boyfriend since.

Her father, who makes a modest living selling automobile parts, paid for the operation even though her mother, a housewife, objected. Ms. Zhang said the cost and the risk of the procedure would eventually prove worthwhile.

"I'm confident the operation will pay for itself many times over," she said, her long pink-painted nails clicking on the pale-blue metal frame of her hospital bed. "I'll have a better job, a better boyfriend and eventually a better husband. It's a long-term investment."