The effect of ketorolac tromethamine, a nonsteroidal anti-inflammatory drug, on normal phagocytosis has been studied. When peritoneal macrophages, taken from mice treated intraperitoneally 4 times daily for 7 days with 2 mg ketorolac per day, were cultured ex vivo or when untreated macrophages were cultured with 1-10 microM of ketorolac in vitro, the number of engulfed Candida albicans was no different from saline-treated or untreated controls. In contrast, macrophages from mice treated intraperitoneally 4 times daily for 7 days with 0.4 mg dexamethasone per day or cultured with 1-10 microM dexamethasone had a greater than or equal to 54% reduction in phagocytosis (p less than 0.001). Thus, ketorolac is a nonsteroidal anti-inflammatory drug which does not inhibit the phagocytic activity of murine mononuclear phagocytes.