In 62 oral mucosa biopsies of different localization and diagnoses, immunohistochemically investigated with the APAAP technique, the OKM5 expression on keratinocytes was connected with the epithelial keratinization. In parakeratotic epithelia, an obvious CD36 upregulation was detectable. Surprisingly, there was no correlation between neither the state of inflammation nor the diagnoses and the OKM5 keratinocyte expression; the oral localization by itself appeared to be responsible for the CD36 expression.