The present study assessed the effects of gross motor activities on the self-injurious tantrums of three multihandicapped subjects. The tantrums did not seem related to specific environmental events and were rather infrequent, yet very severe. The study was carried out according to a withdrawal (ABAB) design. During baseline, the subjects executed routine activities that required minimal physical effort. During treatment, they performed gross motor activities that required considerable physical effort. These activities were designed to provide a wide variety of sensory (e.g., tactile, proprioceptive) input, but without tiring the subjects excessively. They were implemented when the subjects were in a quiet state. The results showed that concomitant with treatment, all subjects had a definite decline in the rate of self-injurious tantrums. Two subjects also exhibited a reduction in the duration of the tantrums.