Objective: To evaluate the short and long term benefits of a school and home based physical activity "enrichment" program for children at higher risk of cardiovascular disease as identified by cluster analysis.Study design: During two 10-week school terms, 800 Ii-year-olds took part in a randomized controlled trial with the standard physical activity and nutrition program in six schools, the standard program in a further seven schools but with the addition of physical activity enrichment for higher risk children in those schools, and no program in five control schools. Cluster analysis identifying the 29% or so highest risk children used systolic blood pressure, percent body fat, physical fitness, and blood cholesterol.Results: Fitness improved significantly in program schools, particularly with enrichment in higher risk boys. Substantial improvements persisted 6 months later in girls from program schools. At "Enrichment" schools, cholesterol showed significant benefits in higher risk girls and, 6 months later, in both boys and higher risk girls. Sodium intake and, in girls, subscapular skinfolds were lower in "Enrichment" schools when the program ended, but not 6 months later.Conclusion: Two-semester health programs with physical activity enrichment for higher risk children can produce benefits sustained for at least 6 months. Improvements extend to lower risk children exposed indirectly to the enrichment. Attenuation of effects on diet and body composition in the longer-term suggest the need for on-going programs.