To study whether exercise blood pressure is more closely related to the complications of hypertension than resting blood pressure, 169 patients with essential hypertension, aged 16-66 years, (WHO stages I and II), underwent a graded uninterrupted exercise test on the bicycle ergometer up to exhaustion. BP was measured in intra-arterially. Target organ damage was assessed by eye-fundus grade and by electrocardiographic voltage criteria and T-wave patterns. After adjustment for relevant covariates (age, gender, body height and weight), the manifestations of target organ damage were significantly related to systolic (r ranging from 0.19 to 0.39) and diastolic (r ranging from 0.11 to 0.30) intra-arterial pressure at supine rest. The complications of hypertension were not more closely related to BP during upright submaximal and peak exercise than to resting BP, and exercise BP did not contribute independently from BP at rest to their variance. In conclusion, exercise BP is not better related to target organ damage than BP at rest in patients with essential hypertension.