A retrospective analysis of 128 technically successful percutaneous transluminal renal angioplasty (PTRA) procedures was performed. After the procedures, transient systemic hypertension (TSH) developed in 39 patients. The phenomenon usually occurred within 30 minutes of balloon dilation and always within 2 hours of PTRA. TSH lasted less than 5 hours in 35 patients and never persisted for more than 24 hours. TSH is a self-limiting process and should not be confused with the more sustained hypertension that arises from a complication of balloon angioplasty.