Healthy male albino rabbits [42] weighing around 1 kg were divided into 4 groups. Group I (8) fed on normal stock diet and Group II (8) fed on stock diet plus cholesterol (0.5 gm in 5 ml of olive oil). Group III (15) received stock diet plus cholesterol plus garlic (0.25 gm) juice. Group IV (11) received stock diet plus cholesterol plus onion (2.5 gm) juice. The animals were closely observed and followed for 16 wk. Approximately every 4 wk, blood samples were collected for estimation of various parameters (S. [serum] cholesterol, S. triglycerides, S. lipoproteins, S. phospholipids and fibrinolytic activity). At the end of the experiment, animals were sacrificed and degree of aortic atherosclerosis was graded (grade 0-4) in different groups and compared. Garlic and onion (garlic more than onion) had a significant effect in inhibiting the rise in S. cholesterol, S. triglycerides, S. beta lipoproteins and S. phospholipids and a significant effect in enhancing the fibrinolytic activity. The .beta.:.alpha. ratio was altered favorably and the ratio was kept close to normal. Regarding the degree of aortic atherosclerosis as seen on post mortem, it was significantly less in garlic and onion group when compared with the pure cholesterol group.