Nilutamide is a nonsteroidal antiandrogen with affinity for androgen receptors but not for progestogen, estrogen, or glucocorticoid receptors. Consequently, nilutamide blocks the action of androgens of adrenal and testicular origin which stimulate the growth of normal and cancerous prostatic tissue. Nilutamide has a long half-life which permits once-daily administration. Nilutamide is usually given in combination with surgical or chemical castration using gonadotrophin-releasing hormone (GnRH) [luteinising hormone-releasing hormone (LHRH)] agonists. In castrated patients the addition of nilutamide improves objective response rates, bone pain, urinary symptoms, tumour markers and time to disease progression. The tolerance of nilutamide is generally acceptable. Adverse effects are usually mild and reversible and consistent with androgen depletion. Unexpected but reversible adverse effects of nilutamide include delayed adaption to dark after exposure to bright light, transient increases in transaminases, and more severe but rare interstitial pneumonitis. Thus, nilutamide is a welcome treatment option that may be particularly useful in patients to whom the convenience of once-daily administration is seen as a worthwhile benefit.