Kinetin (50 and 100 mg 1−1) inhibited both the shoot and the root growth. Inhibition of root growth by kinetin is considered to be mainly due to inhibition of protein synthesis. Vitamins of the B groupviz., riboflavin, thiamin, niacin and pantothenic acid are found to be antagonistic to kinetin in reversing the inhibition of protein synthesis of the root. Vitamins, probably by acting as inducers of protein synthesis, antagonized the action of kinetin. The response of kinetin to shoot protein content is different from that of the root.