Introduction: Vitamin D receptors are widespread in brain tissue, and the active form of vitamin D has been documented for its neuroprotective effects. This study was conducted to determine the association between vitamin D level and cognitive disorders. Materials and Methods: This descriptive–analytical cross sectional study was conducted within the framework of the "Amikola Health and Aging Project (AHAP)", (2011-12), conducted on 1616 older people, aged>60 years in the city of Amirkola, Iran. Serum levels of vitamin D were measured in morning blood samples and mental status was investigated using Mini-Mental State Examination (MMSE). Data was analyzed with T test, ANOVA and Chi-square, and P-values <0.05 were considered signif­icant. Results: The mean age of study participants was 68.81±7.1 years. Among them 509 (31.5%) had cognitive impairment and 1103 (68.4%) did not. There was significant association between serum vitamin D level and normal and abnormal MMSE in women (P=0.029), but not in men (P=0.49). Mean serum vitamin D level in participants with normal MMSE was 34.45±32.79 ng/ml and in participants with abnormal MMSE was 32.80±29.39 ng/ml but this finding was not significant (P=0.31). Conclusions: Serum vitamin D level in older persons with normal MMSE was higher than in those with abnormal MMSE, although it was not significant. In this study, there was no association between serum vitamin D levels in older people with or without cognitive impairment.