The pre-therapy serum levels of immunosuppressive acidic protein (IAP) were assayed in patients with cancer of the uterine cervix and ovarium using the single radial immunodiffusion method. These levels were normal in patients with early cancer of uterine cervix (O and Ia stage); in advanced cancer patients they were increased with cancer stage. The serum IAP levels in ovarian cancer were higher than in patients with advanced uterine cervical cancer.