['To investigate the occurrence of adverse blood pressure (BP) events during transurethral microwave therapy (TUMT) for benign prostatic hyperplasia.', 'We conducted a retrospective study of the vital signs of 185 consecutive patients who received TUMT (via 6 devices) at 4 institutions from March 1, 2003, to September 18, 2005. Maximum change, percent change in systolic BP, diastolic BP, mean arterial pressures, heart rate, and oxygen saturation were evaluated.', 'Of the 185 patients, 77 patients (42%; 95% confidence interval [CI], 35%-49%) experienced an increase in systolic BP of more than 30 mm Hg during TUMT; 30 patients (16%; 95% CI, 12%-22%), an increase of more than 50 mm Hg; and 10 patients (5%; 95% CI, 3%-10%), an increase of more than 70 mm Hg. A greater than 20% change in systolic BP from baseline was observed in 95 patients (51%; 95% CI, 44%-58%). Many men experienced multiple events, with an average time of onset of 15.9 minutes into treatment. Significant differences were noted among the devices.'] Does blood pressure surge during office-based transurethral microwave therapy for the prostate?