Comparative histological examination of both liver and the supra-aortic arteries have not previously examined the consequences of atherosclerosis and nonalcoholic fatty liver disease (NAFLD), and their response to diet and atorvastatin therapy. This study evaluates the effects of diet alone or in combination with atorvastatin therapy on the progression/regression of atherosclerosis and its correlation with NAFLD. This research was performed on a cohort of chickens on standard (SD) or hyperlipidemic diets (HD), either with or without atorvastatin therapy. The development of atherosclerotic lesions was assessed by histology, immunohistochemistry and quantitative image analysis and correlated with liver histology. The lowest levels of atherosclerotic lesions were found in animals on the HD for 3 months, followed by 3 months of SD in combination with oral atorvastatin. There was a strong association between the histologic findings of atherosclerosis and those of NAFLD. These studies show that standard diet and atorvastatin therapy can positively affect both arterial and hepatic lesions, influencing the regression of the changes. These results support the hypothesis that NAFLD and atherosclerosis may be actually two aspects of a shared disease and suggest the possibility of regression of both disorders with dietary and pharmacologic manipulations.