In order to explain the physiological conditions in skin diseases by searching the tendency of metabolism of electrolytes, the contents of sodium, potassium, calcium and chlor in serum were measured in 122 cases of various skin diseases. (1) Comparatively many cases of the numerous skin diseases showed the variation of the contents of electrolytes, but it was not always remarkable and constantly regular. (2) In bullous diseases, acquired pigmentary disturbances, diffuse scleroderma and erythroderma, varied the most remarkably, and especially in the 2 former cases was pointed out the evident tendency. (3) In eczema, dermatitis, inflammatory keratosis, erythematodes and cutaneous tuberculosis were often found abnormal values, but very irregular and complicated. (4) In urticaria, drug eruption and erythema exsudativum multiforme showed slight changes. (5) The auther conceived that the metabolism of electrolytes in vivo was so influenced by the several organs, especially endocrine organs, and by the autonomous nervous system, that such irregularity of this variation was showed.