tBackground: Disorder in cerebellar structure was reported in diabetes mellitus. B vitamins are involvedin many significant metabolic processes within the brain.Aim of the work: To detect the protective role of vitamin B complex on the histological structure of thecerebellum of experimentally induced diabetic rat.Material & methods: Eighteen adult male Wistar rats were divided into two groups. Group I: normal vehiclecontrol (n = 6). Group II: streptozotocin-induced diabetic rats (n = 12), which was equally divided intotwo subgroups; IIA (diabetic vehicle control), IIB (diabetic vitamin B complex-treated): streptozotocin-induced diabetic rats treated with vitamin B complex (1 mg/kg/day) for 6 weeks. Specimens from thecerebellum were processed for light and electron microscopy.Results: In vitamin B complex treated group, the histological changes in Purkinje cells, astrocytes andoligodendrocytes were improved compared with the diabetic non-treated group. The white matterrevealed intact myelinated axons. Inducible nitric oxide synthase (iNOS) and caspase-3 expressionreduced. Glial fibrillary acidic protein (GFAP) expression revealed less activated astroglia. The num-ber of Purkinje cells/mm2significantly increased. While, the number of GFAP positive astrocytes/mm2significantly decreased. In addition, the blood glucose level was reduced.Conclusion: Vitamin B complex protected the cerebellum from the histological changes which occurredin STZ- induced diabetic rats.