In this study, cyanide and thiocyanate levels in blood and ürine samples optained from mice which were injected different doses sodium nitroprusside, were determined. The cyanide and thiocyanate levels in the blood and ürine samples were colorimetrically established oxidation of cyanide and thiocyanate by bromine water and coupling of pyridine-benzidine solution. The cyanide levels in blood and ürine respectively, arrived the maximum levels at 40 min. and 8 h. The thiocyanate levels in ürine of this animals arrived the maximum levels at 48 h. The thiocyanate levels decreased at the small portion after 96 h. and were the same levels for several days. The thiocyanate levels in blood arrived the maximum levels at 80 min and were the same levels for several days.