Impairments of mitochondrial functions is a major feature of polyQ diseases resulting in cell death through activation of apoptotic cascades. The process of mitochondrial dysfunction in polyQ diseases is accompanied by enhanced free radical production and oxidative damage and abnormal energy metabolism. Furthermore, expanded polyQ proteins have been reported to impair axonal trafficking, which possibly results in abnormal mitochondrial distribution and function providing additional causal link between mitochondria and polyQ diseases. Based on multiple studies, it can be recognized that mitochondrial impairment is a common feature in the polyQ diseases pathogenesis.