Wistar male rats were fed from weaning a methyl-deficient diet (groups I and II) or a standard commercial diet (groups III and IV). At the day 3 the left ureter was tied and divided in animals of groups I and III, while those in groups II and IV were sham operated. Rats of all groups were killed on days 8 and 10 to evaluate the incidence and extent of tubular necrosis (day 8) and tubular and cortical necrosis (day 10). The results of this study show that unilateral ureteric obstruction diminishes the incidence, severity and extent of necrosis in the same kidney.