Immunomodulation using medicinal plants can provide an alternative to conventional chemotherapy for a variety of diseases especially when host defense mechanism has to be acquired under the conditions of impaired immune responsiveness. The objective of the present study was to investigate the immunomodulatory potential of aqueous extract of Trapa bispinosa (TBAE) in immunodeficient experimental animals by studying humoral immunity response, delayed type hypersensitivity reaction, macrophase phagocytosis and percent change in neutrophil counts. Further to evaluate antistress activity, wistar rats were subjected to forced swimming endurance test and chronic cold restraint stress. The result of present study suggests that ethanolic fraction of TBAE could stimulate the cellular and humoral response in animals. The anti-stress and adaptogenic activity exhibited by its ethanol fraction in the study further suggests that its ethanolic fraction may useful in the treatment of several disorders caused by stress by its immunostimulating and immunomodulating properties and also enhancing the homeostasis mechanism.