This article reviews the pharmacological properties of tadalafil and the current evidence supporting its use for treating symptomatic benign prostatic hyperplasia (BPH). The rationale for using tadalafil for BPH stems from the following three observations: first, the prevalence of lower urinary tract symptoms (LUTS), BPH and erectile dysfunction (ED) increases with age; second, phosphodiesterase-5 (PDE5) inhibition mediates smooth muscle relaxation in the lower urinary tract; and third, early clinical evidence demonstrates that PDE5 inhibitors such as tadalafil are successful in treating LUTS and ED. A shared pathophysiology makes PDE5 a promising target to treat both LUTS and ED. A recent randomised, controlled Phase II trial of tadalafil versus placebo for the treatment of symptomatic BPH revealed that tadalafil dosed once daily was well tolerated and demonstrated statistically significant and clinically meaningful efficacy in the treatment of LUTS secondary to BPH and improved erectile function in men with both LUTS and ED. The ability to treat both BPH and ED with one medication is noteworthy given the significant negative impact in quality-of-life measures these disorders have in ageing men. Careful patient selection and further trials are warranted.