OBJECTIVE To determine the plasma homocysteine and von Willebrand factor levels as markers of endothelial dysfunction in rats with diabetes mellitus induced by streptozotocin. METHODS Thirty-five adult male rats (Rattus norvegicus albinus) (weight between 180-200 g) were randomized into three groups: control group (n=10), which received no drugs or vehicles; sham group (n=10), which received streptozotocin solution; and diabetic group (n=15), which received streptozotocin. Eight weeks after diabetes mellitus induction, the animals were weighed and anesthesized; blood samples were collected from abdominal aorta for plasma total homocysteine, von Willebrand factor and glucose levels. RESULTS The experimental model was reproducible in 100% of animals. The mean plasma homocysteine levels were: 7.9 micromol/l (control), 8.6 micromol/l (sham) and 6.1 micromol/l (diabetic), with difference among the groups (p<0.01). Multiple comparison analysis among the groups showed that values in the diabetic group were lower than in the sham group (p<0.01). The mean von Willebrand factor values were 0.15 U/l (control), 0.16 U/l (sham) and 0.18 U/l (diabetic), with difference among the groups (p=0.03). The mean value was higher in the diabetic group than in the control group (p<0.05). Correlation between homocysteine and von Willebrand factor was not observed in the diabetic group. CONCLUSIONS Reduced homocysteine levels and increased von Willebrand factor levels were observed in diabetes mellitus induced by streptozotocin; nevertheless, there were no correlations between them and with final glucose levels.