Background/aim: F2 alpha-isoprostane is accepted as an oxidative stress indicator and melatonin shows neuroprotective effects by antioxidative and antiamyloidogenic influences. By measuring these in patients diagnosed with minimal cognitive impairment (MCI) and Alzheimer-type dementia, we intended to demonstrate whether the measurement of these markers contributes to early diagnosis of Alzheimer disease (AD) in the MCI stage or not.