The formation of capsular contracture around silicone implants continues to be the most common complication of augmentation mammaplasty. To date, the etiologic factors in the formation of capsular contractures have remained inconclusive. In the present study, the role of subclinical infection with S. epidermidis as a cause of capsular contracture was evaluated in 16 rabbits using miniature silicone implants. All the implants on the side contaminated with varying concentrations of S. epidermidis developed breast capsular contractures. Using Baker's classification, they were graded III or IV, while the controls were all considered to be either grade I or II. Grossly, the capsules on the contaminated side were firm, fibrous, and 2 to 3 times thicker than the controls, and this was confirmed histologically using micrometry. Implants contaminated with 10(7) bacteria uniformly extruded. The present study seems to indicate that subclinical infection with Staphylococcus epidermidis may be one of the causes of capsular contracture around breast implants.