Serum CEA [carcino/embryonic antigen] and ferritin levels were determined in patients with cervical cancer by radioimmunoassay. Elevated CEA values were found in 9% of stage O-I patients and 50% of stage II-IV. Elevated ferritin levels were found in 16% of stage 0-I and 68% of stage II-IV. determination of serum ferritin levels were more sensitive in detecting cervical cancer than serum CEA. When serum CEA levels and ferritin levels were simultaneously determined, 1 of 13 patients with stage 0, 1 of 10 with stage I, 20 of 28 with stage II and 19 of 20 with stage III had elevated CEA and/or ferritin levels. In 29 patients whose resected specimens were examined to ascertain the extent of the disease, all 12 patients with parametrial invasion and 10 of 11 with lymph node metastases had 1 or both levels elevated. Determination of serum CEA and ferritin levels cannot serve as a test for the diagnosis of early cervical cancer even if both tests were performed simultaneously. An elevated serum CEA or ferritin level in patients with stage I and II indicates a greater likehood of parametrial invasion and/or lymph node metastasis.