Streptozotocin has been used extensively to produce an experimental animal model for diabetes mellitus. The present study was undertaken to investigate the protective effect of camel milk, in comparison to thymoquinone, against streptozotocin-induced damage in the pancreas. The rats were divided into four groups as follows. (1) Control group, (2) Diabetic group with a single intraperitoneal injection of streptozotocin (50 mg/kg body weight), (3) Diabetic group treated with camel's milk (CM) orally and daily at a dose of 2 ml/rat, (4) Diabetic group treated with thymoquinone (TQ) orally and daily at a dose of 50 mg/kg body weight. After 2 months, the animals were sacrificed and blood samples were collected for the detection of serum glucose levels. The pancreas was prepared for histopathological, immunohistochemical and ultrastructural studies. The histological examination of diabetic pancreas showed vacuolation and shrinkage of the islets of Langerhans. The exocrine part of the gland showed vacuolization and flattening of the lining epithelium of the acini. Dense collagen fibres around the acini, blood vessels and pancreatic ducts were also detected. The immunoreactivity or anti-insulin antibodies was markedly decreased. Electron microscopic examination of the diabetic group showed marked changes in pancreatic acini represented by dilatation of the rough endoplasmic reticulum, decrease of secretory granules, vacuolization of the cytoplasm, damage of the mitochondria, and dilatation of the perinuclear space. The β-cells of the diabetic rats showed decrease in the number of secretory granules, heterochromatic nuclei and cytoplasmic vacuolation. CM and TQ improved the histological and ultrastructural changes of the β-cells and exocrine acini epithelium, which almost reverted to their normal structure. These factors increased insulin immunoreactivity and decreased the elevated glucose concentrations. However, insulin immunoreactivity was found in the majority of the pancreatic islets in diabetic rats treated with CM or TQ.