Prostate cancer is a public health problem of the elderly men. It has been estimated that one in six men will develop prostate cancer in his lifetime in the USA. There is thus a huge clinical demand for effective therapies for the prevention and treatment of the disease. Here, the scientific evidence supporting the effectiveness of melatonin in inhibiting the development and progression of prostate cancer is reviewed. The rational use of melatonin in prostate cancer prevention, stabilization of clinically localized favourable-risk prostate cancer and palliative treatment of advanced or metastatic tumour is discussed within the context of the molecular pathogenesis of the disease.