The distribution of succinic dehydrogenase and glucose‐6‐phosphate dehydrogenase in human gingival epithelium was studied using a unidirectional scanning method of microspectrophotometric evaluation. The quantitative analysis was directed to obtain information on the mean enzymatic content of gingival epithelium in different areas and localization of layers of different enzymatic concentration within each epithelial area explored.Glucose‐6‐phosphate dehydrogenase had its maximum content in epithelium of marginal gingiva and lower contents in oral mucosa epithelium, crevicular epithelium and epithelial attachment.uccinic dehydrogenase content was greater in attached gingiva than in all other zones. Glucose‐6‐phosphate dehydrogenase increased its concentration from the basal to the superficial layers in attached and marginal gingiva, remained stable in all strata of oral mucosal epithelium and crevicular epithelium and reduced its activity towards the surface in epithelial attachment. Succinic dehydrogenase decreased its concentration from the basal to the superficial layers i