In this study, induction of diabetes in adult male albino rats by subcutaneous injection of alloxan was done, to evaluate its effects on some blood vessels (Aorta,Femoral and Renal arteries). Thirty adult male albino rats were divided into two groups, diabetic group, and control group, fifteen animals each. After 6 weeks rats were operated and paraffin as well as frozen sections of samples from the Aorta, Femoral and Renal arteries were prepared and stained with different histological and histochemical stains. Histological examination and statistical evaluation of the aorta of diabetic group has showed marked intimal thickening caused by infiltration of smooth muscles, which appear vacuolated. Moreover, the subintimal layer of the media has showed marked proliferation of smooth muscles, with thickened, fragmented elastic fibers, and increased collagen content. The mean ratio of the total areas occupied by collagen fibers was 18.5±1.6, and that of the smooth muscles was 19.8±1.0 in the media. That in turn was significantly increased (P<0.01) when compared to the control group (8.1±1.0) and (12.9±0.9) respectively. Also, the mean thickness of the adventitia was 258.8±4.0, and the mean number of fibroblasts was 41.5±1.7, was significantly higher than those in the control group(P<0.01), which were 185.4±3.4 and 13.1±1.3 respectively. Histochemical results have showed presence of fatty material in the intima and media. Also, the mean optical density (O.D.) values of PAS positive materials was (0.36±0.01), which was significantly increased (P<0.01) than that of the control group (0.32±0.01). Similar results have been also detected in the femoral artery. Furthermore, the renal artery has showed thickening and fragmentation of the external elastic lamina. In conclusion,diabetes has a damaging effect on blood vessels leading to impairment of their functions.