According to the fact that the Synthesis of Co-carboxylase from Vit. B(1) takes place in the liver, and in the case of Vit. B(1) deficiency the insufficiency of the liver function could often be observed, therefore. the close relation between Vit. B(1) and liver function could be presumed. I have examined the relation between Vit. B(1) and liver function in 71 cases of various dermatologic diseases, according to Takata's reaction, hepatosulphalein method and urobilinogen reaction in urine, as the examination of liver function and obtained the following results. 1) 55.6% of the cases in which the blood level of Vit. B(1) was below 6.0γ% showed liver dysfunction, especially the allergic diseases such as eczema, urticaria and prurigo tended to liver dysfunction, and the similar tendency could also be seen in Duhring's dermatitis, pemphigus and pellagra. 2) 66.7% of the cases in which the blood level of Vit. B(1) was above 6.0γ% showed normal liver function, and chloasma, alopecia areata, verrucae planae juveniles and trichophytia showed normal function. 3) In acne vulgaris, erythema induratum Bazin, erythematodes and psoriasis vulgaris no definite relation between Vit. B(1) and liver function could be observed. 4) Including allergic dermatoses, in the dermatologic diseases which tend to exsudation, both positive urobilinogen reaction and deficiency of Vit. B(1) could be observed in many cases. 5) Among the 3 reactions for the examination of liver function, the hepatosulphalein method concured closely with blood level of Vit. B(1). 6) Approximately 90% of the cases had both normal liver function and normal Vit. B(1) value, and 90% with liver dysfunction and deficiency of Vit. B(1). Etiology of many skin diseases are still unknown, and in the relation of Vit. B(1) deficiency and the liver dysfunction to the cause of various dermatologic disorders, the cause and the result are also not clear, but according to my experiments it could be said that the Vit. B(1) deficiency and the liver dysfunction play an impostant roll in the cause and course of some dermatologic disorders.