This paper describes the effects of nitrofen (Hi-TOK), a herbicide on the fetuses of rats. The results were observed as follows: The internal soft tissue anomalies were classified as diaphragmatic hernia, cardiac malformation (T.G.V., V.S.D., S.V.), dilatation of ventricle in brain, dilatation of renal pelvis, underdevelopment of fetal lung, shortening of cortex length and increasing of immatured glomeruli counts in the fetal kidney. The heart and diaphragm appear to be the target organs.