OBJECTIVETo review the pharmacologic and clinical trial data of the Food and Drug Administration–approved phosphodiesterase 5 (PDE5) inhibitors for the treatment of erectile dysfunction (ED).DATA SOURCESPrimary research and review articles were identified through a search of ScienceDirect, PubMed/MEDLINE, and International Pharmaceutical Abstracts (1990–August 2004). The following search terms were used in the Medicine Dentistry and Pharmacology, Toxicology, and Pharmaceutical Sciences subcategories: phosphodiesterase 5 inhibitor, PDE5 inhibitor, erectile dysfunction, sildenafil, vardenafil, tadalafil, prostatectomy, and diabetes. Web of Science (1990–August 2004) was used to search for additional abstracts using the same search terms as above. The package inserts for sildenafil, vardenafil, and tadalafil were also consulted.STUDY SELECTION AND DATA EXTRACTIONAll identified research, review articles, and abstracts were assessed for relevance, and all relevant information was included. Priority was given to the primary medical literature and clinical trial reports.DATA SYNTHESISED is a common disorder in males with increased prevalence associated with age and presence of cardiovascular disease, prostatectomy, or diabetes mellitus. Sildenafil, vardenafil, and tadalafil are selective PDE5 inhibitors currently available for treatment of ED. Their pharmacology and pharmacokinetics vary slightly, but with potentially important clinical differences in duration of activity; all have similar clinical efficacy and adverse effect profiles in patients with ED of various causes.CONCLUSIONSSildenafil, vardenafil, and tadalafil are safe and effective PDE5 inhibitors for the treatment of ED.