Objective: The Iigation of the left renal vein (LLVR) in man is a contraversial procedure in view of the risks of lesion to the renal parenchyma. With the objecUve of studying the morphologic and functional alterations caused by these lesions, we conducted experimental research with rats. Material and Methods: 64 male adult EPM 1-WISTAR rats were used, divided into 8 groups -4 for . LLRV and four for control. Each LLRV group and corresponding control group were sacrificed progressively on the 7th, 15th, 30th and 60th day after the initial surgery. Results: We found morphofunctional alterations only in animais that underwent LLRV in the four periods of sacrifice. The proteinuria creatinine in serum, testosterone in serum and serum corticosterone in serum showed practically no alteration in relation to the normal values for rats. Statistically significant severe histological lesions were found in the kidneys and testes of the LLRV groups. Lesions in the suprarenal glands were also presentin these groups, but no sufficient to demonstrate statistical significance Conclusion: Based on these results we can conclude that the Iigation of the left renal vein is a procedure of high risk in these animais.