Both the production and regression of experimental atherosclerosis, as influenced by eating habits, were studied in the chicken. Birds were either allowed free access to food 24 hours/day ("nibblers") or only for two one-hour periods per day ("meal eaters"). In the induction experiments, it was found that the meal eaters exhibited double the serum cholesterol levels and seven times the severity of coronary atherosclerosis as the nibblers. In studies designed to explore the effects of these eating habits on the regression of established atherosclerosis, lesions were induced in the usual way by feeding an atherogenic diet under the conditions of meal eating. Then the birds were put on regular mash and divided into two groups: meal eaters and nibblers. Meal eating a regular mash diet was associated with (a) slower rate of fall of serum cholesterol levels to normal, and (b) a marked decrease in the rate of healing of the coronary lesions as compared to nibbling. It is concluded that the manner of ingestion of the diet plays a significant role in accentuating the production and in inhibiting the regression of experimental atherosclerosis.