Progesterone receptor analysis has been used to enhance the prognostic usefulness of estrogen receptor analysis in breast cancer. Immunocytochemical assays for both steroid receptors have been shown to correlate with established biochemical techniques but lack long term clinical follow-up studies to validate their use. One hundred fifty- two patients were followed for up to 10 years after primary surgical treatment. Steroid receptor analyses, using both biochemical and immunocytochemical techniques were performed on their tumor specimens. Patients with estrogen or progesterone receptor positive tumors had longer survival than patients with negative tumors. This difference was most clearly demonstrated with immunocytochemical analysis of estrogen receptors (p = 0.04). The two methods for progesterone receptors gave very similar results. Use of multivariate analysis revealed that ER by immunocytochemical analysis was the only significant predictor of prognosis when all four variables were considered simultaneously (p = 0.04). This study suggests that immunocytochemistry gives comparable results to biochemical analysis for progesterone receptors but that immunocytochemical analysis of estrogen receptors was the stronger single prognostic indicator of the four.