Primary breast cancer tissue and lymph nodes were obtained from 48 patients. Estrogen receptors (ER) and progesterone receptors (PgR) were determined by a dextran-coated charcoal assay. ER were present in 72.9% of the primary tumors and in 62.4% of the malignant lymph nodes, whereas PgR were present in 73.0% and 50.0% of the cases, respectively. The primary tumor and the corresponding malignant lymph nodes showed an identical ER and PgR status, i.e., both tumor sites were receptor positive or both receptor negative in 89.6% and 77.1%, respectively. However, 10.4% of the patients had ER-positive tumors but ER-negative lymph nodes and 22.9% had PgR-positive primaries with PgR-negative lymph nodes. No receptor-positive lymph nodes showed a combination with receptor-negative primary tumor. This preliminary data shows that receptor-positive malignant lymph nodes mostly display the same receptor status as the corresponding primary tumor, whereas receptor-negative lymph nodes may have a receptor-positive primary tumor.