The objective of the present study was to detect the expression of P-cadherin in human endometrium and endometriosis and to compare this expression to that of E-cadherin. To this end immunohistochemistry with monoclonal antibodies specific for P-cadherin and E-cadherin was applied to endometrium and endometriotic lesions obtained in the early follicular phase of the menstrual cycle from 10 patients. P-cadherin was detected in epithelial cells in all ten endometrial samples and in all glandular structures of endometriotic lesions. The staining characteristics for P-cadherin and E-cadherin were similar. P-cadherin may play a role in the maintenance of the proliferative compartment of endometrium and could have a comparable function in endometriotic lesions.