In previous experiments (Monserrat, Gotelle, and Garay, 1969) we have found that the administration to rats of a single injection of 1.12 M sucrose induces a hydropic reversible vacuolation of the proximal convoluted tubules of the kidney. Along with the vacuolation the PAS and acid phosphatase positive, as well as autofluorescent granules (lysosomes) disappear and vice versa. We now report the effects of multiple intraperitoneal injections of 1.12 M sucrose. The aim of the study was to determine whether the renal cells are able to adapt to this situation or the modifications are permanent. Wistar male rats were allotted to 4 different groups (A : experimental, B, C, and D, controls) and placed in metabolic cages. Animals from group A were injected with 3.0 ml/100 gm body weight of 1.12 M sucrose at 0, 24, 48, 72, and 96 hours after the beginning of the experiment; rats of groups B and C were injected respectively at 0 and 96 hours, and finally, rats of group D were used as normal controls. All rats were killed at 120 hours. The results showed a striking vacuolation in the proximal convoluted tubules of the rats of group C, and complete regression of vacuolar changes in those of group B. Rats of group A, although they maintained the osmotic diuresis, showed mild vacuolation with persistence of acid phosphatase and PAS positive granules, as well as autofluorescent droplets (lysosomes). We postulate that these results are indicative of adaptive changes, whose mechanisms are at present being studied.