There is substantial evidence of morphological, biochemical and molecular abnormalities in mitochondria in various tissues of patients with Alzheimer's disease (AD). However, the precise role of mitochondria in the neurodegenerative cascade leading to AD is still unclear, leaving the answer to the question "what's first: the chicken or the egg?" pending. Here we focus our attention on the progress made in this field in the past few years, which indicates a key role of this fossil organelle and of its specific DNA in contributing to the disease.