BACKGROUND:: Capsular contracture remains one of the major problems following prosthetic implantation of the breast, especially in postmastectomy breast reconstruction patients receiving radiation therapy. Advances in this area have been hampered by the absence of an acceptable animal model. This study evaluates a new murine model with which to facilitate research into the cellular and molecular pathways underlying capsular contracture and provides a surrogate for evaluating potential therapies. METHODS:: On day 0, mice were implanted with silicone gel implants. Postoperatively, animals were imaged using live-scan micro-computed tomography. Animals in the irradiation group then received a 10-Gy directed radiation dose from a slit-beam cesium source. On days 21, 28, 35, and 42, both irradiated and nonirradiated animals were imaged again and histologic evaluation was performed. RESULTS:: Nonirradiated implants demonstrated little change in contour from day 0 through day 42 on micro-computed tomography, whereas irradiated implants demonstrated consistent shape deformation and irregularities in contour at these time points. Histologic evaluation showed that irradiated specimens developed thicker capsules and more disorganized capsules than nonirradiated specimens at each time point. CONCLUSIONS:: In this article, the authors introduce a novel animal model with which to study capsular contracture. This model is the first of its kind to use radiation to induce, and live-scan micro-computed tomography to evaluate, capsular contracture. Radiation was shown to cause reproducible changes that can be consistently evaluated with micro-computed tomography and histology. Future studies with this model will study the cellular and molecular mechanisms underlying capsular contracture using knockout and transgenic mouse strains.