The present investigation was undertaken to study whether tumor-associated macrophages ofDaltons lymphoma (DL), a spontaneous transplantable T cell lymphoma can be activated totumoricidal state by alcoholic extract of Tinospora cordifolia (ALTC). In vivo administration ofALTC (200 mg/kg body weight) in DL-bearing mice resulted in an enhanced RNI production andan augmented cytotoxic response of tumor-associated macrophages. Earlier we had reported that DL-bearing mice show a regression of thymus and an enlargement of spleen. In vivo administration ofALTC to DL-bearing hosts resulted in a decrease in the weight of spleen and counts of splenocytes alongwith an increase in the weight of thymus as compared to control DL-bearing mice. In vivoadministration of ALTC in DL-bearing mice also resulted in an increase in the proliferation ofsplenocytes/thymocytes and BMC. The results of this study indicate that the ALTC upon in vivoadministration in DL-bearing shows immuno-modulatory effects and thus may have clinicalsignificance.