Capsular contracture is the most common and frustrating complication in women who have undergone breast implantation. Its cause and, accordingly, treatment and prevention, remain to be fully elucidated. The aim of this prospective observational study was to test the hypothesis that the presence of bacteria on breast implants is associated with capsular contracture. We prospectively studied consecutive patients who underwent breast implant removal for reasons other than overt infection at the Mayo Clinic from February through September 2008. Removed breast implants were processed using a vortexing/sonication procedure, and subjected to semiquantitative culture. Twenty five of the 45 implants collected were removed due to significant capsular contracture of which 9 (36%) had > 20 cfu bacteria/10 ml sonicate fluid; 20 were removed for reasons other than significant capsular contracture of which 1 (5%) had >20 cfu/10 ml sonicate fluid (p=0.034). Propionibacterium species, coagulase negative staphylococci and Corynebacterium species were the microorganisms isolated. Results of this study demonstrate that there is a significant association between capsular contracture and the presence of bacteria on the implant. The role of these bacteria in the pathogenesis of capsular contracture deserves further study.