The aim of this study is to examine from a biochernical and histological perspective, whether vanadium has a protective effect on the pancreas of diabetic rats. Male, 6-6.5 months old, Swiss albino rats were divided into four groups. Group 1: control (intact) animals (n = 13). Group II: control rats given vanadyl sulfate (n = 5). Group III: streptozotocin-induced diabetic animals (n = 11). Group IV: streptozotocin-induced diabetic animals given vanadyl sulfate (n = 11). Vanadyl sulfate was given by gavage technique to rats in a dose of 100 mg/kg daily for 60 days, after experimental animals were made diabetic. On day 60, the pancreas tissue and blood samples were taken from the animals. In the streptozotocin-induced diabetic group, blood glucose levels significantly increased in contrast to the loss of body weight, but vanadyl sulfate in streptozotocin-diabetic rats reduced blood glucose levels and increased both blood glutathione levels and body weight. Tissue sections were immunostained using an insulin antibody. The control group given vanadyl sulfate was no different from the other intact control group considering the insulin immunoreactivity in B cells. In pancreatic islets of the diabetic group, a decrease in the number of immunoreactive B cells was observed in comparison to the control group. On the other hand, pancreatic islets of the diabetic group given vanadyl Sulfate showed a higher number of immunoreactive B cells in comparison to the diabetic group. According to the immunohistochemical and biochernical results obtained, it was concluded that vanadyl sulfate call regenerate B cells of endocrine pancreas in experimental diabetes. (c) 2005 Elsevier Ireland Ltd. All rights reserved.