A considerable amount of experiments on various animals has been made to study the mechanism and the nature of the renal complication induced by each of the sulfa drugs. In this studies, the author made an experiment of sulfathiazole on rabbits using the renal clearance test to see the effects on renal function. 1. The amounts of urine and the glomerular filtration rate were not influenced by the administration of 0.05 g, 0.10 g, 0.20 g per 1 kg weight of rabbits for 10 days. 2. The renal plasma flow, renal blood flow and hematocrit were clearly deoreased and the filtration rate showed temporarily increase.