Hypertension is associated with impaired left ventricular (LV) diastolic function. However, the impact of stress on LV filling of treated hypertensive individuals is unclear. Fourteen hypertensive patients (mean age 55 years) and 14 age-sex matched normotensive controls underwent Doppler echocardiographic studies at rest and one minute following supine ergometer bicycle. The evaluations were done before and under treatment with diltiazem (180 mg/ day) during 24 weeks. Resting blood pressure control was achieved under treatment. However, the pressure-rate product was unchanged during exercise. Left ventricular mass index decrease from 153 ± 7 to 129 ± 8 g/m 2 (p < 0.01). There was a significant increase in the resting peak velocity of early filling (E) (57 ± 3 VS. 48 ± 4 cm/s, p < 0.01) and E/A ratio (1.1 ± 0.1 vs. 0.9 ± 0.1, p < 0.01) while peak velocity of late filling (A) remained unchanged (56 ± 4 vs. 57 ± 3 cm/s). The deceleration time was Shortened (p < 0.05). With exercise, percentage of change in E (%E) and E/A (E/A%) were lower in patient than control group (21 ± 6 vs. 37 ± 8 and 5 ± 5 vs. 21 ± 12 respectively; p < 0.05 for both). The treatment didn't improve these differences. These findings suggest that LV filling in response to stress remain blunted in treated hypertensive patients.