In the present study, we have characterized the cell surface receptors for transforming growth factor-β (TGF-β) on monolayer cultures of stromal cells prepared from human endometrial biopsies, and on a human endometrial epithelial cell line (RL95-2) using affinity cross-link labeling techniques. On the stromal cells, five TGF-β binding proteins were identified. Analysis of the sensitivity of these proteins to dithiothreitol and phosphatidylinositol-specific phospholipase C, together with results from immunoprecipitations with antibodies against the type II and III TGF-β receptors, confirmed that three of these binding proteins correspond to the cloned type I, II, and III TGF-β receptors. The other two binding proteins observed exhibit the characteristics of isoform-specific GPI-anchored TGF-β binding proteins. On RL95-2 cells, three TGF-β binding proteins, corresponding to the type I, II, and III TGF-β receptors, were identified. The receptors which we have characterized on endometrial cells are responsive to physiological concentrations of TGF-β as demonstrated by the effect of TGF-β on endometrial cell proliferation. Accordingly, these receptors have the potential to respond to the TGF-β isoforms which have recently been detected in the endometrium in an autocrine and/or paracrine manner.