Benign prostatic hyperplasia (BPH) can have a profound affect on a patient's quality of life and sexual function and is considered by patients to be one of the most important aspects affected by the disease. Different treatments can produce a variable response in terms of the patient's quality of life, including sexual activity and satisfaction. Varying rates of erectile dysfunction (ED) and retrograde ejaculation following surgery for BPH have been reported. In general, the incidence of these side-effects is less after minimally invasive therapies, such as interstitial laser coagulation and transurethral microwave therapy, but the data available are limited. The lowest rates of sexual dysfunction are reported with medical therapies. The 5a-reductase inhibitor, finasteride, can result in ED in 5 -9% of patients and ejaculation disorders in 0.8 -2.0%. With the exception of tamsulosin, a 1 blockers are associated with a low rate of sexual dysfunction. No cases of ED have been reported with alfuzosin and abnormal ejaculation with terazosin or alfuzosin is negligible. Indeed, early research suggests a beneficial effect of a 1 blockers on sexual function. In addition to information on the efficacy of a particular therapy, patients should be informed of side effects, in particular those relating to sexual function, in order that they can make informed treatment decisions. Prostate Cancer and Prostatic Diseases (2001) 4, Suppl 1, S12-S16.