The generating capacity of interleukin 1 (IL-1) and interleukin 2 (IL-2) by peripheral blood mononuclear cells (PBMNC) was measured in 40 patients with digestive cancer (20 localized and 20 disseminated) and 20 age- and sex-matched control subjects. The localized carcinoma patients showed normal IL-1 production and a significantly depressed IL-2 production (p less than 0.05) when compared to the healthy individuals. The disseminated carcinoma patients exhibited a significant impairment of both IL-1 and IL-2 production in comparison with the healthy controls (IL-1: p less than 0.001, IL-2: p less than 0.001) and the localized carcinoma patients (IL-1: p less than 0.001, IL-2: p less than 0.001). A significant correlation was observed between IL-1 and IL-2 generation in all the cancer patients (r = 0.458, p less than 0.01). These results suggest that progressive tumor growth may result in decreased interleukin production by the host PBMNC, and that related mechanisms, which are more susceptible to lymphocytes than monocytes, may be involved in the impairment of both IL-1 and IL-2 production.