Highly purified 40S- and 60S-subunits of the eukaryotic ribosomes from the rabbit liver have been found to hydrolyze ATP. Their hydrolytic abilities were compared and the effect of the inhibitors: ammonium metavanadate and alkaloid emetine has been studied. Data presented may reflect the existence of a single site for ATP on the 80S-ribosome which is located on the regions of contact between 40S- and 60S-subunits.