The goal of the present study is to evaluate the histological effect of Coenzyme Q10 (CoQ10) in the liver and buccal mucosa in mice.After acclimatization to the laboratory conditions, Twenty-four mice were randomly assigned to three experimental groups and housed as eight animals/cage, and each group was treated as follows: Group A: this served as a control group and was given daily olive oil orally. Group B and C were given once daily CoQ10 in dose (100mg /kg) and (200mg/kg) respectively. All groups were treated for 15 days and at the last of the experiment, all animals of each group were sacrificed and liver in addition to buccal mucosa was excised and placed in 10% buffered formalin for histological examination. In CoQ10 treated groups a normal histological structure similar to control group in liver and buccal mucosa sections were noticed at the CoQ10 (100mg/kg) group while mild histological changes were noticed at the CoQ10 (200mg/kg) group included slightly congested portal vein and sinusoids, mild centric lobular vacuolar swelling in the hepatic lobule and buccal mucosa sections showed normal structure as control group.CoQ10 at a dose (100mg/kg) not produce any histological changes in the liver and buccal mucosa in mice but when increasing the dose to (200mg/kg) produce mild histological changes in liver but not in the buccal mucosa.