Groups of 12 male Japanese quail (Coturnix coturnix japonica) of a strain susceptible to experimental atherosclerosis (SEA) were fed one of three purified diets (one basal and two atherogenic) for 8 wk. The basal diet contained: glucose (46%), soy protein (35%) and beef tallow (10%). Atherogenic diets were prepared by replacing glucose with either 1% cholesterol or 1% cholesterol plus 0.5% cholic acid. Both atherogenic diets induced hypercholesterolemia, with serum cholesterol increased 202 and 336% above basal values for birds fed the cholesterol and cholesterol/cholic acid diets, respectively. The hypercholesterolemia was characterized by an increase in serum levels of very low density and low density lipoprotein cholesterol. No atherosclerotic lesions were found in birds fed the basal diet, but lesion incidence in the dorsal aorta and brachiocephalic arteries was 75 and 100% for birds fed the cholesterol and cholesterol/cholic acid diets, respectively. Arterial scores (percentage of arterial surface area covered by lesions), arterial cholesterol concentration and total liver cholesterol were significantly higher (P less than 0.05) for birds fed the cholic acid containing diet than for those fed the diet having cholesterol only. Severity of atherosclerotic score and arterial cholesterol concentration were positively correlated (P less than 0.01 in both cases) with serum cholesterol concentration. The two indices of the severity of atherosclerosis (arterial score and arterial cholesterol concentration) were highly and linearly correlated (r = 0.88, P less than 0.01). The SEA strain of quail appears to be a promising model for the study of atherosclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)