Abstract: Cholesterol was fed daily to 47 white male rabbits (0.5 or 3 g/kg) and 107 domestic pigeons of both sexes (1, 3 or 6 g/kg) for 1, 2, 3 or 4 months. An arbitrary scale of 0 to 4 was employed for visual grading of the aortic plaques. The mean scales in different groups were compared by t test. In rabbits, the duration and dosage of cholesterol feeding were closely related to the atherogenesis. The model receiving 3g/kg/day for 3 months seemed to be more reliable, the mean scale in 10 rabbits being 2.7±1.3. Daily feeding of 0.5 g/kg for 4 months also yielded a severe lesion, which, however, awaits further verification. Supplement of thiouracil, amphetamine, nicotine, calciferol, Ca-lactate, Na-cholate, and sucrose to the cholesterol resulted in (a) an acceleration of the plaque formation, (b) an elevation of serum cholesterol at the end of 1 month 22 times the control level, and (c) a high mortality. In general, rabbits developed atherosclerosis easier than pigeons, but were liable to die. In pigeons, daily feeding of cholesterol 3g/kg with methylthiouracil 0.1 g/pigeon for 3 months led to a high scale, amounting to 1.5±1.2 for 11 pigeons. Yet its high mortality impels modification of the amount and duration of its feeding. Half starvation could not be confirmed to hasten the atherogenesis. When the daily dosage of cholesterol exceeded 3g/kg, the enteral absorption appeared to be poor. No difference in degree of atherogenesis was observed between the sexes of pigeons. Two synthetic drugs, Na-cinnamate (Ⅰ) and phenelzine (Ⅱ), and two chinese drugs, "Compound Mixture of Two Fairies" (Ⅲ) and the fluid extract of Berberis spp. (Ⅳ), were daily fed by mouth. Though the differences among the therapeutic activities of the 4 drugs were statistically non-significant, evidences were suggestive that Ⅰ and Ⅲ appeared to be preferable to Ⅱ and Ⅳ. These 4 drugs were started since the second month of cholesterol-feeding. In the future screening of drugs an earlier start of therapy is recommended.