Abstract Peritonitis caused by Candida albicans is a major complication of continuous ambulatory peritoneal dialysis (CAPD). Increasing the activity of the peritoneal macrophages- the predominant cell type found in the peritoneal cavity-may be of great importance in the prevention and therapy of peritonitis. Therefore, the activating effect of tuftsin was studied on human peritoneal macrophages from CAPD patients. Tuftsin induced a biphasic effect on macrophage activity within a range of 2×10 − 9-2×10 − 6M, with a maximal activity 2×10 − 7M. At this concentration,tuftsin enhanced by twofold cell association with radiolabelled candida (from 2±0.2 to 4±0.2 candida per macrophage) and superoxide anion production in response to exposure to candida (from 150±20 to 300±20 nmoles/mg). These results suggest the potential use of tuftsin as a therapeutic drug.