Ductal carcinoma in situ (DCIS) is a highly heterogenous tumor that is now more frequently diagnosed because of the increased number of screening programs. Women with DCIS are mainly treated with conservative surgery almost always followed by radiotherapy. Although conventional biomarkers, i.e. ER, PgR, Ki67, and HER2, have been extensively investigated in invasive tumors, little is known about their role in DCIS, especially that of the androgen receptor (AR). In the present study, the expression of conventional biomarkers and AR was determined by immunohistochemistry in 85 DCIS samples from patients monitored for a maximum of 13 years: 43 patients were treated with quadrantectomy and 42 patients underwent quadrantectomy and radiotherapy. Of these, 5 and 11 patients relapsed, respectively. Our findings showed that ER and PgR were higher in nonrelapsed than in relapsed patients (P=0.025 and 0.0038). In contrast, AR expression and the AR/ER ratio were higher in relapsed patients than in the nonrelapsed group (P=0.0069 and 0.0012). At the best cut-off value of 1.1, the AR/ER ratio showed an overall accuracy of 92% and 80% in predicting in situ relapse or progression to invasive carcinoma in DCIS patients treated with surgery and those treated with surgery plus radiotherapy, respectively. AR would therefore appear to be an independent prognostic biomarker in the latter group. Our preliminary results highlight the potentially important role of the AR/ER ratio as a predictive indicator of DCIS relapse, independently of treatment.