CEA and TPA were studied in sera and in histologic specimens of 200 patients with benign (77) or malignant (123) breast pathology. The frequency and expression of the two markers was different in benign and in cancer tissues. Histologic positivity and high levels of circulating markers were observed more frequently in cancer patients than in patients with benign disease. Tissue positivity for the two tumor markers did not always correlate with elevated levels of circulating markers. Positive CEA and TPA incidence was higher in tissue samples than in serum samples. In the breast cancer group, among 33 patients with histologic positivity for CEA, only 5 cases had circulating CEA levels higher than 5 ng/ml; among 91 patients with histologic positivity for TPA, only 45 cases showed circulating levels for TPA higher than 95 U/l. These findings confirm that tumor size, secretory characteristics and vascular supply are factors affecting the achievement of high circulating marker levels. Combined marker measurement in serum and tissues can provide more information about the presence of a given tumor marker. A limited evaluation of the prognostic meaning of the study of combined CEA and TPA in sera and in tissues was carried out during the follow-up of 60 evaluable patients. Only 5 patients had cancer relapses in the first 12 months from surgery; in 2 of 5 patients TPA was positive initially and at the time of recurrence, in serum as well as in tissues. Circulating CEA gave negative findings in all relapsed patients; 2 of them showed weak positivity only in the histologic staining at the time of presentation.