Mice immunized by a series of intravenous, intraperitoneal or subcutaneous injections of formalin-killed Leishmania donovani promastigotes with glucan, a β1, 3 polyglucose, exhibited a significant degree of resistance against subsequent infection with viable promastigotes. Intramuscular immunization was not effective. Immunization via subcutaneous injections of dead promastigotes simultaneously with glucan elicited protective resistance, positive skin test responsiveness before and after challenge and increased antipromastigote antibody levels. Injections of glucan alone induced a lesser degree of resistance against infection without significant skin test or humoral responsiveness. Injections of dead promastigotes alone elicited increased antibody levels but no skin test responsiveness or resistance against infection.