Systolic blood pressure (SBP) normally increases during exercise. This increase is frequently exaggerated in hypertensive individuals. The aim of our study was to evaluate the antihypertensive effects of losartan at peak exercise and on cardiac performance during the treadmill test in individuals with essential hypertension. Forty subjects with a mean age of 44.2 +/- 12.4 years and with mild-to-moderate essential hypertension were enrolled. After a 14-day washout period, all selected subjects were given a treadmill exercise test using the modified Bruce protocol for exercise. The test was performed at the end of the washout period (step 0), again after 1 month (step 1), after 3 months (step 2) and after 6 months (step 3) of losartan administration (50 mg/daily per oral). Heart rate, SBP and diastolic blood pressure (DBP) were measured at rest and at maximal exercise. Exercise duration and double product were also recorded. In all patients who completed the study, a significant reduction from baseline in SBP at rest was found at 3 and 6 months (p < 0.05). No significant reduction from baseline in SBP at peak exercise was observed. No significant changes from baseline were found in double product, DBP, heart rate or exercise time. The results of our study suggest that losartan is effective in reducing blood pressure only at rest but is unable to improve exercise BP response or cardiac performance in subjects with mild-to-moderate essential hypertension.