Erectile dysfunction is usually of vascular origin and is frequently encountered in men with cardiovascular disease. The introduction of phosphodiesterase-5 inhibitors has revolutionized the management of patients with erectile dysfunction. Currently available phosphodiesterase-5 inhibitors have distinct pharmacokinetic and pharmacodynamic properties, thus permitting for tailoring sexual therapy according to patient characteristics and needs. Phosphodiesterase-5 inhibitors possess vasorelaxing properties and exert systemic hemodynamic effects, which need to be taken into account when other cardiovascular drugs are co-administered. Special caution is needed with alpha-blockers, while the co-administration with nitrates is contra-indicated due to the risk of life-threatening hypotension. This review presents the advent of sexual therapy, describes the mechanism of action and the specific characteristics of commercially available phosphodiesterase-5 inhibitors, summarizes the efficacy and safety of these drugs with special emphasis on the cardiovascular system, and discusses the clinical criteria used for the selection of each drug for the individual patient.