CoQ10 is an essential cofactor of the electron transport chain and is a potent free radical scavenger in lipid and mitochondrial membranes. CoQ10 has shown efficacy in treatment of Parkinson's disease patients, and a Huntington's disease trial gave a trend of slowing down disease progression (CARE-HD). A small trial of CoQ10 in patients with Friedreich's ataxia suggested potential beneficial effects on ventricular thickness. CoQ10 is being tested on ALS patients and is considered to be potentially useful for treatment of Alzheimer's disease. Thus, CoQ10 is considered to be a promising therapeutic agent that might slow down the disease progression in a wide variety of neurodegenerative disorders. To date, very high doses of CoQ10 have not been used in patients with ataxia and the safety and tolerability in this group of patients should be established before efficacy trials are launched.