Background:green tea is one of the most popular beverages in the world. Green tea is a non-fermented tea that contains a large amount of non oxidized polyphenols, named catechins which has been found to be effective in preventing different diseases.Many studies have been done to detect the effects of green tea extracts on various body systems. Aim of work:Our research aimed to study the possible effect of green tea in treatment of streptozotocin induced diabetes mellitus by studing its effect on rat pancreatic cells.Material an methods:A number of 15 adult male albino rats ( group I) then subdivided in to three groups group I control, group II STZ induced diabetics, group III STZ induced diabetics then treated with green tea.Then animals were sacrificed after six weeks and samples of pancreas were taken and prepared for Electron microscopic examination. Results:various histopathological changes are seen on streptozotocin induced diabetes pancreatic cells and these changes become less or near normal on group III treated with green tea after streptozotocin .Conclusion: green tea has protective and therapeutic effects on STZ induced diabetes in rats.So, further investigations on the effect of green tea are recommended. Key word: Insulin ,Green tea ,Pancreas ,Streptozotocin,Diabetes.