Male mice which were allowed wheel exercise during a late stage in the life-span had a small, but statistically reliable increment in longevity, compared with control male mice. Differences in longevity were not statistically reliable for experimental and control female mice. However, longevity was significantly positively correlated with wheel exercise for both male and female experimental mice. The behavioral effects of access to activity wheels were to increase scores of exploration activity and decrease scores of emotionality compared with scores of controls. Albino hybrid mice lived as long as pigmented (brown or black) hybrid mice. The albino gene, as expressed in F2hybrids, was not found to be deleterious for measures of longevity, or behavioral measures of wheel activity, exploration, and emotionality.