It is claimed that exaggerated blood pressure (BP) responses to exercise are predictive of future hypertension and may also be indicative of left ventricular (LV) hypertrophy. The relation between LV hypertrophy and maximal exercise BP was examined in 35 normal male volunteers and 65 untreated hypertensive male patients. Multiple stepwise regression analysis revealed that preexercise systolic BP was the major determinant of maximal exercise systolic BP (r = 0.52; p less than or equal to 0.0001), indicating that higher baseline BP predicted higher exercise BP. However, hypertensive patients with LV hypertrophy had the smallest increases in systolic BP with exercise. Accordingly, there was an inverse relation between LV muscle mass and systolic BP responses to exercise in these patients (r = -0.34; p = 0.005). When compared with normotensive subjects, hypertensive patients had lower measures of maximal oxygen uptake and exercise heart rates (p = 0.01). This may indicate lower cardiac performance at maximal exercise and explain the reduced capacity of hypertensive patients with LV hypertrophy to increase systolic BP with exercise. Neither baseline nor exercise BPs correlated with LV mass; instead, the model of regression analysis indicated that body weight was the principal determinant of LV mass. Contrary to previous reports, exaggerated exercise BPs were not associated with LV hypertrophy in hypertensive or normotensive patients.