A method for calculating Cherenkov radiation intensity from an initial electron energy distribution is presented. The Cherenkov radiation intensity from 1 curie of Sr/sup 90/ in secular equilibrium with Y/sup 90/ in water was calculated from the beta energy spectrum to illustrate the use of the method for a pure beta emitter. The Cherenkov radiation intensity from 1 curie of Co/sup 60/ in water was calculated from the Compton electron energy spectrum to illustrate the use of the method for a gamma emitter. The steps necessary to obtain the Compton electron energy spectrum from a gamma emitter are indicated. (auth)