Recent evidence suggests that angiotensin II may participate in the regulation of inflammation. We therefore studied the effects of angietension II on human peripheral blood mononuclear cell reactivity. Peripheral blood mononuclear cell suspensions stimulated with PHA-P revealed decreased thymidine incorporation when simultaneously cultured for 48 or 72 hours with angiotensin II. Experiments were next conducted to determine whether angiotensin II acted directly on lymphocytes. Complete monocyte depletion (>99.53) resulted in low PHA-P-induced reactivity which was still inhibited by the addition of angiotensin II. Purified (>99.53) lymphocytes incubated with angiotensin II prior to reconstitution of mixed mononuclear cell suspensions led to reduced PHA-P-stimulated thymicine incorporation. These findings suggest that angiotensin II can effect mononuclear cell uptake possibly through actions on the lymphocyte population.