Xenotropic murine leukemia virus-related virus (XMRV) is a gammaretrovirus originally identified in a subset of prostate cancer patients. Because androgens stimulate prostate tumors and some retroviruses, we investigated the effects of dihydrotestosterone (DHT) on XMRV transcription and replication. Transcription from the XMRV U3 region was stimulated up to 2-fold by DHT, but only in cells containing a functional androgen receptor. Mutations in the glucocorticoid response element (GRE) of XMRV impaired basal transcription and androgen responsiveness. Furthermore, DHT stimulated XMRV replication 3-fold, whereas androgen inhibitors (casodex and flutamide) suppressed viral growth up to 3-fold. Findings suggest that integration of the XMRV long terminal repeat (LTR) into host DNA could impart androgen stimulation on cellular genes.