Plasma lipid concentrations and coronary artery atherosclerosis extent were compared in a retrospective study of female cynomolgus monkeys consuming a moderately atherogenic diet and housed in single cages or social groups. There was no difference between single caged and socially housed monkeys in plasma lipid concentrations. However, females housed in single cages had significantly more coronary artery atherosclerosis than those housed in social groups. It has been found previously that socially subordinate females have more extensive coronary artery atherosclerosis than social dominants, and that subordinates spend more time alone than dominants. Subsequent analyses of the data presented here revealed that single caged monkeys had significantly more coronary artery atherosclerosis than socially dominant, but not socially subordinate, monkeys. Characteristics of single cage housing which could be disease promoting include restraint and social isolation. These findings should be considered preliminary, and serve as a basis for further study.