Combined central retinal artery occlusion (CRAO) and central retinal vein occlusion (CRVO) is an uncommon retinal vascular disease which causes sudden visual acuity loss and is associated with poor prognosis and the development of severe complications. We report a very rare case of combined CRAO and CRVO in a patient with factor V Leiden (FVL) mutation (only 3 cases published). To our knowledge, this is the first case of combined CRAO and CRVO treated with hyperbaric oxygen therapy (HBOT). A 49-year-old woman presented with complaints of sudden loss of vision in her left eye (LE), with best corrected visual acuity (BCVA) of 1/20. A complete ophthalmic evaluation with fundus angiography showed combined CRAO and CRVO. The patient was urgently treated with HBOT (she completed a total of 9 sessions in 7 days), with marked visual acuity and angiographic improvement (BCVA of 10/10). Forty-five days later, she developed a new LE CRVO, and BCVA decreased to 5/10 and later to <1/20 because of significant macular edema. A detailed investigation showed an abnormal resistance to activated protein C, and a genetic study showed homozygosity for FVL mutation. The patient was submitted to 3 monthly injections of 1.25 mg bevacizumab. After 10 months, the patient is in a stable condition with BCVA of 6/10. Combined CRAO and CRVO in young adults should be investigated thoroughly for embolic sources, thrombophilic disorders and local ocular conditions. This is the first case of this severe disease that was treated with HBOT, and the visual result was very good. Lemos, Teixeira, Carvalho, Fernandes, , , , , (). Combined Central Retinal Artery and Vein Occlusion Associated with Factor V Leiden Mutation and Treated with Hyperbaric Oxygen. Case reports in ophthalmology, ;6(3):462-8. https://www.ncbi.nlm.nih.gov/pubmed/26955350