The induction of invertase from beetroot plants and wheat shoots was studied using the "ageing tissues" technique. It was found that ammonium sulfate at concentration 0.001 M enhances invertase induction. This effect of ammonium sulfate was not revealed when the preparations were pretreated by actidione, puromycin and chloramphenicol. A possibility of activation of invertase induction by ammonium sulfate is discussed.