J. Neurochem. (2008) 104, 1613–1621. Abstract Coenzyme Q 10 (CoQ 10 ) is a promising agent for neuroprotection in neurodegenerative diseases. We tested the effects of various doses of two formulations of CoQ 10 in food and found that administration in the diet resulted in significant protection against loss of dopamine (DA), which was accompanied by a marked increase in plasma concentrations of CoQ 10 . We further investigated the neuroprotective effects of CoQ 10 , reduced CoQ 10 (ubiquinol), and CoQ 10 emulsions in the (MPTP) model of Parkinson’s disease (PD). We found neuroprotection against MPTP induced loss of DA using both CoQ 10 , and reduced CoQ 10 , which produced the largest increases in plasma concentrations. Lastly, we administered CoQ 10 in the diet to test its effects in a chronic MPTP model induced by administration of MPTP by Alzet pump for 1 month. We found neuroprotective effects against DA depletion, loss of tyrosine hydroxylase neurons and induction of alpha‐synuclein inclusions in the substantia nigra pars compacta. The finding that CoQ 10 is effective in a chronic dosing model of MPTP toxicity, is of particular interest, as this may be more relevant to PD. These results provide further evidence that administration of CoQ 10 is a promising therapeutic strategy for the treatment of PD.