[Objective]: We have determined Coenzyme Q10 (CoQ10) levels in salivary cells (SCs) and mononuclear blood cells (BMCs) from Fibromyalgia (FM), and we study the influence of oral CoQ10 supplementation on cells levels and clinical symptoms. [Methods]: CoQ10 was determined by high-performance liquid chromatography (HPLC). Ten patients were supplemented daily with 300 mg of CoQ10 during 3 months. [Results]: CoQ10 were reduced in both cell models. Oral supplementation showed an improvement in clinical symptoms and restored levels. [Conclusions]: Patients with FM showed an important dysfunction in CoQ10 levels and might benefit from oral supplementation.This work was supported by Federación Andaluza de Fibromialgia y Fatiga Crónica (ALBA Andalucía).Peer reviewe