Diabetes is increasingly prevalent at global level and associated with various impacts including the male reproductive system. Aims. This research is aimed at investigating the influence of diabetes on the localization and expression of HSP90 and iNOS in the testicular tissue of diabetic rats. Methods. A diabetic model was developed through a single injection of alloxan monohydrate intraperitoneally (purchased from Sigma-Aldrich) 120 mg/kg body weight following fasting for 12 hrs. The experiment involved two groups, the control and diabetic groups with 10 albino rats in each group. Diabetes was considered if glucose concentration was ≥200 mg/dl. The experiment duration was for one month. After the experiment had finished, all rats were terminated and prepared for routine histological and immunohistochemical examination. Results. The results revealed that diabetes caused morphological changes at histological level in testicular tissue. Immunohistochemical examination showed that diabete