This study puts forth the morphological and metabolic modifications that occurred in the skin affected by Pemphigus vulgaris, modifications that have been studied by histoenzymatic techniques. There were studied skin biopsies from patients suffering from Pemphigus vulgaris, hospitalized in Dermatology services in Bucharest. The pieces were sectioned at cryotome, at 3 degrees C and then they were studied with histochemical methods, in order to evidentiate the activity of the following enzymes: NADH(2)-cytochrome-c-reductase, lactate-dehydrogenase (LDH), dihydrofolic-reductase (DHFR), folic acid (FA), ATP-ase pH 9.4, leucin-amino-peptidase (LAP). The enzymatic activity was appreciated in all skin components: epidermal layers, connective tissue cells and inflammatory cells from the superficial and deep dermis, blood vessels, nerve fibers and encapsulated corpuscles. In the affected skin, there were observed modifications of all enzymes studied. The study revealed the following aspects: the balance between oxybiotic and anoxybiotic metabolism in the epidermal cells changes from the predominance of the former in the healthy skin, to the dominance of the latter in the affected skin, an active turn-over of the nucleic acids and increased synthesis of amino acids in the dermal cell population (mainly in the fibroblasts and mast cells), morphological and functional alteration of mitochondria, lysosomes and cellular membranes.