Herein the authors describe characteristics of women with breast implants compared with women with other types of cosmetic surgery as well as population controls. All women who acquired breast implants from 1977 to 1997 were identified from the files of two private plastic surgery clinics in Denmark. Patient characteristics were obtained through a self-administered questionnaire. The magnitude of differences between patient and control groups was estimated using odds ratios and 95% confidence intervals. Women with breast implants had a significantly lower body mass index and reported a two-fold greater incidence of current smoking compared with women from the general population and compared with women with other cosmetic surgery. Women with implants reported a greater number of full-term pregnancies and were less likely than controls to have had their first birth at age 30 years or older. Women with implants were not more likely than women in either control group to report a history of diseases, including connective tissue diseases, cancer, or depression before their implant surgery. Women with cosmetic breast implants differ from women with other forms of cosmetic surgery and from general population controls with respect to several characteristics that may importantly influence health outcomes and that need to be addressed in future breast implant studies.