The effects of a structured physical exercise program on the ward behavior of 16 institutionalized hyperactive children (6 to 13 years old) was investigated. Ss were randomly assigned to conditions in which they ran, engaged in calesthenics, or both, for 20 minutes per day, 5 days a week, for 4 weeks. Data from daily behavioral measures were analyzed and a large statistically significant beneficial effect for running was found. Calesthenics did not improve the children's daily scores. The possible contribution of physiological and psychological factors is considered. (Author/CL)