The experiments were carried out on 15 rabbits od common breed in 3 groups, K--control, 1--unoperated and 2--operated. The weight of the animals before operation oscillated from 3.8-4 kg. Group 1 was fed with standard food with an addition of 4 g cristal cholesterol and 4 g of pork lard for 21 days. The animals in group 2 were fed similarly. This group was operated with 1/3 bypass of the caudal part of the small intestine. After 3 weeks the rabbits of both groups were killed. For biophysical and pathohistological investigations, sections of the right liver lobe, abdominal aorta and the small intestine were taken. Lipids of the liver and aorta wall were analysed chromatodensitographically. The results were statistically analysed and tabulated. In group 1, three times more lipids were found in the liver and about 2 times more in the aorta wall, than in group K. In group 2, the level of total lipids in the liver and in aorta wall was slightly higher than in the control. It was caused by TG and UF in the liver and by CE and UF in the aorta wall. Microscopic observations in group 1 showed diffused, vast multifocal undegenerative steatosis of the liver and considerable lipids infiltration without atherosclerotic plaques in the aorta wall. In group 2, steatosis of the liver was slight and it did not occur in the aorta wall. Normalization of the composition and distribution of lipids was observed in the liver lobules and aorta wall. Partial by-pass of the small intestine was in atrophy because of inactivity in the presence of a relative multiplication of mucocells.