Clinical studies have demonstrated that sildenafil citrate (Viagra) is an effective and well-tolerated oral treatment for erectile dysfunction. Despite its established safety profile, concern about its cardiovascular safety persists among some physicians and the general public. This concern has stemmed primarily from sporadic reports of adverse events published in the literature and sensationalized by the media. However, the only absolute contraindication for sildenafil is concurrent use of nitrates. Because sildenafil has been on the market for 4 years and under clinical investigation for even longer, we can now evaluate its long-term safety in men who have been taking the drug for several years. We review this issue from 3 perspectives. First, we reassess the overall safety profile of sildenafil by reviewing the initial controlled clinical trials and open-label studies. We present new data from patients who have been exposed to sildenafil for up to 4.5 years. We also evaluate the results from independent postmarketing studies. Second, we review the cardiovascular-specific results from the clinical trials, long-term extension, and postmarketing studies. Lastly, we review the specific effects on the visual system based on findings from studies conducted during drug development and post marketing.