OBJECTIVE Our objective was to assess the cell-to-cell contacts in hyperplastic human endometrium and to compare them with contacts in normal endometrium. METHODS Hyperplastic endometrial samples (five with simple hyperplasia and five with complex hyperplasia) without atypia by light microscopy were studied with transmission electron microscopy. The cell-to-cell contacts, basal lamina, and epithelial-to-stromal compartment contacts were studied and compared with these same areas in normal endometrium. RESULTS Only infrequent gap junctions between epithelial cells were seen. Other epithelial contacts were also greatly reduced when compared with normal epithelium. Cell-to-cell contacts between the epithelial compartment and the stromal compartment were rare and degenerative in configuration. An increase in extracellular matrix and various alterations in the basal lamina appears to contribute to a decrease in cell-to-cell contacts. CONCLUSIONS Compared with normal endometrium, hyperplastic endometrium demonstrated far fewer cell-to-cell contacts. The basal lamina and extracellular matrix were altered in such a fashion that communication between the stromal and epithelial compartments appeared to be impaired. Stromal and epithelial cells rarely were in contact. Those contacts present were less complex and the majority were degenerative. Hyperplasia without atypia demonstrated a much lower amount of intercellular communication than normal endometrium.