Phosphodiesterase 5 inhibitors are cardioprotective against myocardial reperfusion ischemic injury in animal models but are contraindicated in patients with coronary disease who take nitrates because of a risk for hypotension. We investigated the safety of vardenafil in patients undergoing coronary artery bypass grafting (CABG) surgery. A single dose of vardenafil was given to 10 patients before CABG surgery. The postoperative course of these 10 patients was compared with the postoperative course of 47 patients who did not receive vardenafil before CABG surgery. There were no perioperative deaths and no episodes of hypotension in the group receiving vardenafil. The clinical and operative characteristics of the 2 study groups were similar. There were no significant differences in postoperative serum troponin levels (9.1 ± 8.3 vs 12.5 ± 9.3 ng/mL; P = 0.29, respectively), duration of postoperative intubation (21.4 ± 10.1 vs 27.4 ± 15.2 hours; P = 0.14, respectively), or length of hospital stay (11.1 ± 13.2 vs 10.0 ± 4.7 days; P = 0.8, respectively) between the group receiving vardenafil and the control group. This pilot study of 10 patients suggests that vardenafil use is safe in patients before CABG surgery. A larger study is needed to explore the myocardial protective effect of the drug.