Laminin receptor 1 may have a role in the progression from endometrial hyperplasia with or without atypia to endometrial cancer. Therefore, we aimed to investigate the pattern, percentage, and intensity of laminin receptor 1 expression in normal, hyperplastic, and neoplastic endometrium. Paraffin blocks of 131 specimens with the diagnoses of normal endometrium (n=25), endometrial hyperplasia with atypia (n=21) or without atypia (n=55), and endometrial cancer (n=30) were immunostained with laminin receptor 1 antibody, and its expression percentage, pattern, and intensity in the epithelial cytoplasm, basement membrane, and endometrial stroma of these tissues were assessed. When compared with hyperplasia with or without atypia and endometrial cancer, the percentage of nonstaining with laminin receptor 1 in the epithelial basement membrane was higher (96%), and the percentage of <50% staining with laminin receptor 1 was lower (4%) in the normal endometrium (P=0.001). While a progressive increment in staining percentage and density of epithelial cytoplasm and basement membrane was noted through an orderly progression from normal endometrium to endometrial hyperplasia without atypia, endometrial hyperplasia with atypia, and cancer of endometrium (P<0.001), such a relationship was not found for the staining percentage and density of endometrial stroma (P>0.05). Disease progression-related gradual increment in laminin receptor 1 expression in the epithelial basement membranes of hyperplastic endometrium with or without atypia and cancer of endometrium reveals that it may play a substantial role in the transition from premalignant to the malignant state of endometrial lesions.