Abstract: The develapmerit af diabetes neuropathy has nat been deeply investigated in animais in wich diabetes mellitus is genetically determined, specially in the lineage af NOO mice. This lineage cJovelaps diabetes type 1 as a cansequence af the autaimmune destructian af thE:) Islets af Langerhans. This work had the purpase af characterize marfalagically the tibial, fibular and sural nerves af the NOO mice from the brazilian calany (NOO/UNI) intending their passible use as experimental sample for the studies of diabetes neuropathy. For this work 20 NOO animais, aged between 19 and 21 weeks, were used, and they were divided into groups af 5 females and 5 males, that have brought out positive glycosuria during the two sequential weeks (OM) and 5 females and 5 males, also aged between 19 and 21 weeks whose glycosuria was negative until the moment af the sacrifice (NO). The glicasuria was manitared each two days from the tenth week of life and diabetic state evaluated by the measure of glycemia levei (2 300mg/dl) immediately before the sacrifice. Another group of 5 male mice from the lineage A/J, aged b_tween 19 and 21 weeks, were taken for comparisan. Afther the animais had been anaesthetized, the tíbial, fibular and sural nerves were isolated for fixation in situ with solution af glutaraldehyde 2% and paraformaldehyde 1 % at a buffer solution of sadium phosphate (ph 7,4). Section of each nerve were pos-fixed in a solution of Os04 (1 %) and processed for inclusion in araldite resin. Using thin transversal cuts, the marphological analysis was dane as well as the counting óf the number of myelinated axans of the tibial, fibular and sural nerves, and the morphalogical characterizatian of the lalter. A camputerized marphametric system was used and it has been abtained the fallowing parameter myelinated fibers af the sural nerves of diabetic animais (OM) and nan-diabetic animais (NO): the diameter af the myelinated axans (AO); fiber diameter (FO); thickness af the myelin sheath (TMS) and the rate "g" (AO/FO). The obtained results bring aut that there are no detectable morpholagical differences among the tíbial, fibular and sural nerves of diabetic and nan-diabetic animais under optical microscopy. In the same way, the total number af myelinated axons found in the analysed nerves was same in the groups studied. On the other hand, the morphometric analysis of the sural nerve made evident a reduction on the diameter of myelínated axons in the diabetic animais males and females if in comparison to those of the non-diabetic animais (p>O,OS). The diameter of the fibers also pointed out a reduction in diabetic animais. Nevertheless the thickness of the myelin sheath had been statiscally similar in diabetic and non-diabetic animais. The rate "g"pointed aut a greater number of myelinated fibers bringing out a extramyelinization, specially in the female diabetic animais. Those results showed that the diabetic condition in NOO animais, lasting from 2 to 3 weeks, IS able to cause morphometric alterations in the sensitive nerves. Therefore, the mice of NOO lineage can become a good studying model of the effects of diabets hyperglycemia on sensitive nervous component in a short lapse of time Ver menos