Benign enlargement of the prostate is a malady of older males, reaching an estimated prevalence of 90% in patients aged over 70 years. Many of these patients are treated with alpha blockers, which can lower blood pressure significantly. We report on a 64-year-old man who developed a right hemiparesis after taking one dose of doxazosin 4 mg for prostatic symptoms. A CT scan of the brain and carotid ultrasound studies were normal. He recovered most of his neurological function within a few days. Ambulatory blood pressure monitoring on doxazosin 2 mg revealed a striking sleep blood pressure reduction.