Using a low protein diet (aproximately 2%), two experiments were performed trying to reproduce the morphologic and electrophoretic (serum proteins) findings known to ocurr in infantile malnutrition. The model shows in young albino rats the major lesion seen in humans, standing between kwashiorkor and marasmus. The consequence of the diet is well seen by the stationary body weight. Atrophic dermal lesions were seen after 30 days. The most striking lesion was a perilobular fatty liver. Hepatocellular regeneration was abortive appearing in the final stages with regressive changes. It was possible to stablish a gradation of pancreatic changes, from small zimogenic degranulation in the begining to severe acinar atrophy after 30 days of diet, with subversion of its normal frame. The intestinal changes which ended in atrophy not comparable with that of humans, correspnd to reduction in height of the mucous epithelium, hipocellularity of the lamina propria, small crypts, decreased number of mitoses, shortening of the villi giving them a resemblance of the "germ free" animals mucosal pattern. Besides this, the authors call attention for the important decrease in size and number of the goblet cells in the ileum and in the large bowel. The model also shows a lympho-histiocitic depletion, seen by the atrophy of Peyer's patches, decrease of Kuppfer cells, thymic, lumph node and spleen lymphoid depletion. The biochemical study of the serum, has revealed a low total protein and cholesterol. The electrophoretic study has shown a decrease o albumin, with A/G inversion. Alfa1 and Alfa2 globulins were increased in the deprived animals, while Beta and Gama did not show significant difference. These findings may be atributed to protein deficiency because the control groups, even those with caloric restriction, have not presented lesions or changes of the serum proteins.