Capsular contracture, constrictive tightening of scar tissue around implants, was historically the primary reason for reoperating breast-implanted women. Yet, capsular contracture remains of unknown etiology. Contamination with foreign material is one of several suspected causes. Talc, a known fibrogenic agent, was recently found in peri-implant scars. A comparison of 192 explanted women was designed to investigate the role of talc in the induction of capsular contracture. This study included women implanted with silicone gel-filled implants for whom tissue samples were available. Patients were evaluated for the occurrence of capsular contracture and the presence of intracellular talc particles in peri-implant tissues. There was a significant association between talc and capsular contracture (odds ratio = 18.0, 95% confidence interval = 5.9-55, P < 1 x 10(-9)). This study indicates that talc was a major risk factor for capsular contracture in women augmented before 1992.