The effect of radiation therapy on the final result of breast reconstruction has been debated in the literature. We have had 4 patients with bilateral breast reconstruction who then received unilateral radiation therapy. We noted in all 4 that the irradiated side became contracted, whereas the nonradiated breast reconstruction remained soft. These 4 patients were compared with the bilateral breast reconstruction not receiving radiation therapy. The contracture rate in this control group was 10% (19 of 190 breasts). The difference in contracture rate between these two groups was significant (p=0.05). A second group of patients was reviewed, unilateral reconstruction patients receiving radiation therapy to the reconstructed breast. This group was compared with bilateral reconstructions not receiving radiation therapy as a control group. The contracture rate in the unilateral reconstruction group receiving radiation therapy was 67% (7 of 11), versus the control of 10%. This difference is also significant (p=0.001). We conclude that radiation therapy of prosthetic breast reconstruction does increase the rate of capsular contracture. Therefore, we counsel our implant reconstruction patients that the risk of capsular contracture is increased if subsequent radiation therapy is required.