We report on alterations in IL‐2 production and cell proliferation following PHA stimulation of peripheral blood lymphocytes (PBL) from stage‐1 endometrial carcinoma (EC) patients, and on mechanisms involved in these alterations. Our study includes 3 groups: EC patients, post‐menopausal women at high risk of developing EC, and age‐matched healthy women. IL‐2 production was markedly lower in most EC patients than in healthy controls. Varying levels of IL‐2 were produced by PBL from women in the high‐risk group. The proliferative response of PBL to PHA appeared to correlate with levels of IL‐2 production. Our results suggest that macrophages are involved, in part, in the modulation of T‐cell functions of EC patients.