Since salt-sensitivity to blood pressure (BP) response is a species-related phenomenon, the response of BP to dietary sodium was examined in 14 adult male African green monkeys (Cercopithecus aethiops). The animals were exposed to graded increase of dietary NaCl at 0 (control), 3.0, 4.5, and 6.0%, respectively for 45, 139, 37, and 90 days. Systolic and diastolic BP and body weights were measured twice weekly. Body weight did not differ significantly between successive diets. The mean (+/- SD) systolic/diastolic BP for control, 3.0, 4.5, and 6.0% NaCl diets were 88.8 +/- 15.4/65.9 +/- 13.7, 101.9 +/- 17.6/72.1 +/- 13.0, 90.5 +/- 20.9/62.2 +/- 16.2, and 115.3 +/- 22.6/81.0 +/- 16.4, respectively. BP changes between successive diets were significant (p less than 0.05). Monkeys with high or low initial mean arterial BP levels on control diet tended to maintain the same order with significantly high correlations between BP levels for successive diet periods (r = 0.88 to 0.95, p less than 0.0001). Thus as a group, this nonhuman primate species responds to increased NaCl intake with elevated mean systolic and diastolic BP. Individual variations in salt sensitivity and consistency in persistence of BP levels in this species has bearing on human hypertension.