Endophthalmitis is a rare infection of the vitreous and/or aqueous. It can be bacterial or fungal. Exogenous endophthalmitis is the most common form and results from direct inoculation of a pathogen after eye surgery or penetrating trauma. Endophthalmitis can also be endogenous, secondary to disseminated infection. Fungal endophthalmitis is associated with poor prognosis and treatment is difficult given the low penetration of most of the antifungal agents available and the emergence of resistant filamentous fungi like Fusarium. To our knowledge, we describe the first endogenous fungal endophthalmitis due to Fusarium dimerum, a ubiquitous pathogen found in soil and plants. A 71-year-old woman, diagnosed with acute myeloid leukemia, was hospitalized for surveillance after induction chemotherapy. Prophylaxis by antibiotics and posaconazole was ongoing when she complained of pain and decreased vision in the left eye. A voluminous chorioretinal abscess developed and after multiple sterile aqueous humour samples, only vitrectomy allowed diagnosis with fungal hyphae seen on May-Grünwald Giemsa stained smear and positive cultures. The fungus was identified as Fusarium dimerum. The treatment, that included intravitreal injections of voriconazole and amphotericin B associated with systemic administration of voriconazole, allowed complete control of the infection. The source of this infection could not be confirmed despite the discovery of several possible infection sites including a periungual whitlow on the left hand and a lesion on a nail, from which samples were negative in microbiology laboratories. Unfortunately, damages of the retina were too important and the patient did not recover sight of her left eye.