The results of experimental studies on vitamin E-deficiency are largely affected by experimental conditions. This study, therefore, was undertaken to establish an exact experimental system for our further investigation of vitamin E-deprived rats. Wistar rats of either sex, weighing 40-60 g., were fed for a period from 12 to 25 weeks with a vitamin E-deficient diet mainly composed of corn starch, lard, casein (vitamin-free), dried yeast and salt mixture. The control animals were of two types; those fed with deficient diet but given oral supplements of alpha-tocopheryl acetate (30mg. daily) and those reared with a commercial stock diet. The growth curve of the experimental group shows that there was almost normal gain during the first 8 weeks, but from the 10th until the 19th week, retardation of the increase in body weight was apparent, and since then the body weight began to decrease most. Some changes were also observed in the general appearance of the rat deficient in vitamin E. The histological examination revealed pathological changes in the tissues of central nervous system, muscle, liver, skin and genitals. However, as to these several lesions, we could not deny the possibility that other causative factors than vitamin E-deficiency might also be concerned with such microscopic changes. We have obtained some valuable observations on adequate experimental conditions of breeding method or nutrition, which would make a significant contribution to our further experiments.