Individuals with mental retardation (MR) typically exhibit lower levels of cardiovascular fitness than their non-disabled peers. However, there seems to be a gap in the literature with respect to comparative studies between younger children with and without MR. The present investigation compared cardiovascular fitness levels of youth with and without MR. Sixty young (30 with MR, 30 non-disabled) performed a 20-m shuttle run designed to assess cardiovascular fitness. Results indicated that non-disabled children exhibited significantly greater levels of aerobic fitness than did those with MR. Findings illustrate the need for critical examination of physical activity programs for children with MR, as lags in fitness evidenced versus non-disabled peers approximately 50 years ago still exist