We developed an autoradiographic screening test for hormone sensitivity of single cell suspensions of tumor tissues on cell mats, which inhibited the growth of normal cells alone. We applied this method to our newly established KSE-1 line derived from esophageal carcinoma and compared this method with well-established cytoplasmic and nuclear assays. Our assay, though taking longer to implement and providing only qualitative information, requires significantly smaller specimens than the current biochemical assay and will predict the hormone sensitivity of only viable neoplastic cells.