Cisplatin and paclitaxel are potent antineoplastic agents. Their distinctly different mechanisms of action have prompted laboratory and clinical research into their use in combination therapies. Murine peritoneal macrophages treated with cisplatin and paclitaxel in combination elicit an increase in their number of lysosomes. Drug-treated macrophages, when co-incubated with sarcoma 180 cells, establish cytoplasmic contact and transfer lysosomes into tumor cells causing tumor cell lysis. In addition, analysis of tissue culture supernatants show increased levels of interleukin-1alpha and tumor necrosis factor-alpha. Our study shows that cisplatin and paclitaxel in combination enhance elements of the immune system with greater efficacy and potency than when used alone.