After liposuction, breast augmentation is the most popular cosmetic surgery in the United States. In 1999 alone, about 167,000 women had the procedure, according to the American Society of Plastic Surgeons. Surveys show that most are happy with their results, but that finding doesn't mean surgery and recovery are risk-free. According to one study, 60 percent of women who got implants experienced at least one complication within four years. Here are five points to ponder before going under the knife.

Implants don't last a lifetime. The largest study to date found that nearly one third of the women had their implants removed and/or replaced within three years. The most common reasons: leakage and/or rupture of the implant; capsular contracture (when the scar tissue that forms around the implant tightens, causing hardness and pain); and asymmetrical, wrinkled or scared breasts.

Future mammograms may not be accurate. Implants can block breast tissue from view during mammography, which could delay or hinder a diagnosis of breast cancer.

Breast-feeding may be impossible. Milk ducts may be severed during the operation. Certain surgical techniques may prevent this, but many doctors advise that you postpone surgery if you want a guarantee.

Long-term risks aren't known. Most of the concerns about systemic health problems - like lupus or rheumatoid arthritis - revolve around silicone-filled devices, which are rarely used today for cosmetic surgery (though saline implant shells are made of a type of silicone). A review of several studies indicates, however, that these conditions are not more common in women who have implants than in those who don't. Still, some experts believe that further investigation is needed.

You need an experienced doctor. Interview a few surgeons. Ask how long they've been doing the procedure, how many they perform a year, what kinds of complications they see most often and how frequently they have to reoperate. There are no "right" responses, but you should feel comfortable with the answers. - Hilary Macht Felgran

For more information, go to www.fda.gov/cdrh/breastimplants. This brings you to the Food and Drug Administration's Web site.

Sources: Walter Erhardt, M.D., president of the American Society of Plastic Surgeons; Mia Talmor, M.D., plastic surgeon at New York Presbyterian Hospital; Diana Zuckerman, Ph.D., president and director of the National Center for Policy Research for Women and Families.