Background: It was previously reported that vitamin B12 (Vit B12) has the regulatory effects on epidermal growth factor (EGF) and tumor necrosis factor alpha (TNF-α). The role of Vit B12, EGF and TNF-α in the pathogenesis of alzheimer dementia has not been elucidated yet. In this study the plasma Vit B12, EGF and TNF-α level were examined in individuals, between 65-99 years old with and without alzheimer dementia (AD). Methods: The study group comprised 47 patients with AD and 38 cases without dementia. EGF and TNF-α were analyzed by ELISA, and Vit B12 was analyzed by chemiluminescence method. Results: Vit B12 and EGF levels were significantly lower (p Conclusions: Our results suggest that Vit B12, EGF and TNF-α may have a role in the pathophysiology of AD.Key words: Alzheimer dementia, Vitamin B12, Epidermal growth factor, Tumor necrosis factor alpha