A 59-year-old man with prostate cancer and erectile dysfunction underwent uncomplicated laparoscopic prostatectomy. His only other medical problem was depression, treated with buproprion hydrochloride. The immediate postoperative hematocrit measured 25.2%. The patient was ambulating and hemodynamically stable on postoperative day 1 and that evening took 20 mg of tadalafil. Fifteen hours later, he reported dizziness lasting several minutes. Blood pressure and pulse measured 126/61 mm Hg and 99 bpm, respectively. The episode resolved spontaneously. Forty-five hours after ingesting tadalafil, he noted sudden, persistent “graying” in the inferior visual field of the left eye. The next day, he took 20 mg of tadalafil. The graying did not change.