In an attempt to identify biologic markers that might predict prognosis in breast cancer patients, the presence or absence of seven tumor-associated antigens in 54 infiltrating breast carcinomas was correlated with tumor recurrence rates (minimum five-year follow-up), axillary lymph node metastases and tumor volume. Immunohistochemical kappa-casein was present in 30 (56%) tumors, alpha-lactalbumin in 39 (72%) tumors, secretory component of IgA in 26 (48%) tumors, carcinoembryonic antigen in 34 (63%) tumors, pregnancy-specific beta-1-glycoprotein in 7 (13%) tumors, beta subunit of human chorionic gonadotrophin in 1 (2%) tumor and human placental lactogen in 0 (0%) tumors. There was no significant correlation between the presence or absence in tumor of any of the antigens, and prognosis as assessed either by 5-year recurrence rates (P greater than 0.18) or by the presence of axillary lymph node metastases (P greater than 0.20). No significant difference was noted in mean tumor volume (cm3) +/- SEM, between tumors with or without antigen immunoreactivity (P greater than 0.05).