At present, a significant proportion of patients with prostate cancer are diagnosed at an early stage and may receive treatments able to bring about the long-term control of the disease. Thus, the impact of available treatments on the patient's quality of life has been gaining increasing importance; for patients with prostate cancer, counselling on the treatment-related effects on sexual function has become mandatory. Radical prostatectomy is very frequently performed in patients with clinically localized prostate cancer. Postoperative erectile function has been reported as being satisfactory in the majority of the patients operated on in centers of excellence for this procedure. However, overall, the results for postoperative potency are disappointing in view of the large amounts of data available from community practices. Attempts to improve postoperative potency include the intraoperative use of cavernous nerve stimulation and grafting of peripheral nerves to restore the innervation of the corpora cavernosa. Erectile dysfunction has also been associated with prostate radiotherapy. It has been shown that both ultrasound-guided brachytherapy and three-dimensional conformal radiation therapy cause an impairment of erectile function that is usually seen some time after the completion of therapy. Treatment with sildenafil citrate remains a viable option both for patients treated with radical prostatectomy (in whom the cavernous nerve function is at least partially present) and in patients treated with radiotherapy.