Among mammals, the Chiroptera (Bats) have been perhaps the least studied with respect to systematic accounts of immune responses. To resolve this omission in comparative immunology, we have begun to analyze aspects of immunity of the large frugivorous bat, Pteropus giganteus with respect to antibody secreting plaque forming cells and serum antibodies as measured by haemagglutination titres. Homologous complement was more effective than guinea pig or rabbit complement in lysing SRBC for developing plaques. Kinetic of antibody response to three different doses of SRBC has been studied. We observed a peak primary response and its decay after a single antigenic challenge which were notably delayed, and a same dose of antigen could produce 2-Mercaptoethanol resistant PFC and HA-tires.