In the series of salicylic acids derivatives investigated 3,5-DIS has a large inductive effect of enzymes with respect to the metabolism of xenobiotics: rise in the rate of Cyt. P 450; increase of ethoxycoumarin deethylase, bilirubin glucuronosyl transferase and benzphetamine-N-demethylase activities. This effect is comparable with that of phenobarbital.