Inhibiting the androgen receptor (AR), a hormone-activated transcription factor, with androgen deprivation therapy is the standard-of-care treatment for metastatic prostate cancer. Paradoxically, potent androgen-mediated activation of AR can also inhibit prostate cancer growth in some patients and experimental systems, but the mechanisms underlying this phenomenon remain to be fully elucidated. In this presentation, new insights into androgen-mediated tumour suppression will be described, including work from our laboratory demonstrating that AR can modulate innate and adaptive immune signalling. Emerging therapeutic strategies to harness the tumour-suppressor activities of AR will also be discussed.