Our goal was to assess a nonhuman primate diet that mimicked the Western-type diet of humans with regard to palatability and the diet's effects on plasma lipid concentrations and other cardiometabolic risk factors. We evaluated male (n = 8) and female (n = 11) African green monkeys (vervets; Chlorocebus aethiops sabaeus) that initially were fed a standard diet. Each cohort then was divided into 2 groups, which received either standard chow or the Western diet. Food consumption and fecal quality were measured weekly. Body weight, waist circumference, and body-mass index were measured every 2 wk. CBC and clinical chemistry analyses were performed at baseline and 4 wk after the diet change. Plasma lipid concentrations, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, insulin, and fructosamine were measured at baseline and at 4, 8, and 12 wk after the diet change. Isoflavones were measured in the male monkeys at 6 wk after diet change, and lipid particle size was measured in the female monkeys at the 12-wk point. Green monkeys readily ate the Western diet and maintained baseline body weight and morphometric measures, with no adverse effects on fecal quality or clinical measures. Total plasma cholesterol was higher in monkeys fed the Western diet compared with standard chow. Isoflavones were higher in male monkeys fed standard chow compared with the Western diet, but lipid particle size did not differ by diet in female monkeys. Our data indicate that the Western diet led to changes in various biomedical risk factors of green monkeys to become similar to those of humans in the United States.