Tea is the most widely consumed beverage in the world, second only to water. Most laypersons and scientists believe that green tea is healthier than black tea due to the low incidence of heart disease and cancer in the Orient. Here, we report the first dose-response comparison of a green and black tea on normal hamsters after long-term supplementation and on a hamster model of atherosclerosis. Both teas were equally effective in inhibiting atherosclerosis with the lower dose decreasing it 26-46% and the high dose decreasing it 48-63%. Atherosclerosis was inhibited by three mechanisms: hypolipemic, antioxidant, and antifibrinolytic. There was a significant correlation between atherosclerosis and the three mechanisms. In the normal animals, teas also caused some improvement in plasma low density lipoprotein (LDL), LDL/high density lipoprotein ratio, triglycerides, lipid peroxides, lower density lipoprotein lipid peroxides, and fibrinogen. Isolated lower density lipoprotein oxidizability was also reduced in all groups. Green and black teas were equally effective at human equivalent doses, thus confirming human intervention and epidemiology studies and providing mechanisms for teas' benefit.