A blood pressure increase was reported in black immigrants from Africa to Western countries. The present study was undertaken to evaluate whether an impairment of the cardiopulmonary reflex might make blacks unable to adapt peripheral vascular resistance to increased sodium intake. Ten normotensive clinically healthy blacks (aged 38+/-6 years) who had recently migrated from Mogadishu, Somalia to Florence and 10 age- and gender-matched healthy white subjects were investigated. Cardiopulmonary baroreceptor reflex was studied after 7 days of normal (108 mEq) and low (30 mEq) sodium intake by assessing forearm vascular resistance (FVR) and central venous pressure (CVP) during the application of lower body negative pressure (LBNP) at -10 and -20 mm Hg. With a normal sodium diet the gain in cardiopulmonary baroreceptor reflex, expressed as the FVR increase per mm Hg of CVP reduction, was significantly lower in blacks than in white subjects (2.6+/-1.1 v 5.1+/-1.1 U per mm Hg of CVP, P < .001). Differences between the groups disappeared with a low-sodium diet because the reduction of the efficiency of the cardiopulmonary baroreceptor reflex was lower in blacks than in whites (2.4+/-0.7 v 3.3+/-0.7 U per mm Hg of CVP, P = .09). In conclusion, the efficiency of the cardiopulmonary reflex is lower in normotensive black immigrants than in whites. The lower adaptation of the cardiovascular system to the Western sodium diet could contribute to reported long-term blood pressure increase.