Capsular contracture is one of the most common complications associated to the use of foreign materials in reconstruction after mastectomy and aesthetic breast augmentation. Many risk factors, causes, and conditions seldom associated with capsular contracture have been identified but none of these have been confirmed by published data. Among these, subclinical infections (particularly those caused by Staphylococcus epidermidis) seem to be one of the most likely. In the present study we analysed the correlation between capsular contracture and the incidence of periprosthetic subclinical infection in two groups of patients who had first-stage breast reconstruction: one group of patients who were not having adjuvant or neoadjuvant radiotherapy for breast cancer (n = 25) and a second group of patients who had had quadrantectomy and radiotherapy (QUART) and successive radical mastectomy for recurrent disease (n = 25). Patients who had radiotherapy had a significantly higher incidence of subclinical infection (n = 13) than patients who did not (n = 1), but there was no statistical correlation between subclinical infection and capsular contracture. Subclinical infections seemed to present at a later stage and under certain local and systemic circumstances that favoured bacterial growth, such as radiotherapy.