Objective To compare the cost effectiveness of sildenafil and papaverine-phentolamine injections for treating erectile dysfunction. Design Cost utility analysis comparing treatment with sildenafil (allowing a switch to injection therapy) and treatment with papaverine-phentolamine (no switch allowed). Costs and effects were estimated from the societal perspective. Using time trade-off, a sample of the general public (n = 169) valued health states relating to erectile dysfunction. These values were used to estimated health related quality of life by converting the clinical outcomes of a trial into quality adjusted life years (QALYs). Participants 169 residents of Rotterdam. Main outcome measures Cost per quality adjusted life year.