BACKGROUND: Epidemiological data link erectile dysfunction (ED) and lower urinary tract symptoms (LUTS), two highly prevalent conditions in men, assuming a common pathophysiology. Preliminary data showed that phosphodiesterase type 5 inhibitors (PDE5i) might be a promising class of drugs also for LUTS.OBJECTIVE: The aim of this review is to provide an overview of current knowledge on the association between ED and LUTS with a particular focus on PDE5i as a viable treatment option for LUTS.METHODS: A Medline search was completed using the Medical Subject Headings (MESH keywords) 'erectile dysfunction' and the expression 'lower urinary tract symptoms' in all fields of the database. This search revealed 122 relevant references (all Medline database until 31 October 2008).RESULTS/CONCLUSIONS: LUTS are an independent risk factor for ED. Although the pathophysiological link between these conditions is not clear, several theories have been described with various levels of supporting data. Current data show that PDE5i reduce obstructive and irritative voiding symptoms but have no effect in uroflowmetry parameters of postvoid residual volume. The combination with alpha-adrenergic antagonists may be another treatment option for LUTS. However, further research is needed to establish efficacy and safety of PDE5i in the treatment of LUTS.