Five adult male stutterers were subjected to electric shock under three conditions. After stuttering frequency was stable in base rate, three subjects were (1) presented electric shock continuously, but the shock was terminated for five seconds contingent on each stuttering (escape); (2) not presented electric shock continuously, but were given a burst of shock contingent on each stuttering (punish); and (3) allowed to choose the shock condition they preferred. Two other subjects followed the same procedure, except that the order of the escape and punish conditions was reversed. The five subjects behaved differently in the various experimental conditions. For three subjects, the percentage of words stuttered changed very little in the escape condition, whereas two subjects' stuttering increased in escape. In the punish condition, the percentage of words stuttered changed very little for one subject, increased for two subjects and decreased for two subjects. Little change in stuttering behavior occurred in the preferred choice condition.