Peripheral blood monocytes and draining lymph node macrophages from patients with squamous cell carcinoma of the oral cavity, monocytes from patients with oral leukoplakia and those from healthy donors were assessed for FcR. HLA-DR expression and interleukin-1 (IL-1) production after activation with LPS or IFN gamma. Monocyte cytotoxicity was also tested after activation with LPS, IFN gamma, IL-2 singly, or in combinations at suboptimal concentrations. The results showed that the percentage of activated monocytes expressing FcR was significantly low in untreated oral cancer patients, however, the proportion of HLA-DR positive cells was normal. The unstimulated monocytes from oral cancer patients showed spontaneous generation of IL-1. Upon activation, few patients could produce IL-1 to normal levels. The unstimulated monocytes from untreated patients and treated patients with recurrence also exhibit significantly higher tumoricidal activity. Treatment of monocytes with combinations of two modulators (IFN gamma, LPS and IL-2) induced significantly higher cytotoxicity.