A 36-year-old female patient presented to our clinic with a two months history of diplopia and dizziness. The symptoms appeared gradually and increased in frequency and intensity. She had no significant medical history and she did not take any medication. A full ophthalmological consult was performed, which revealed restricted ocular motility in the left eye (LE), in left gaze. Otherwise, the examination showed no pathological findings: best corrected visual acuity (BCVA) both eyes (OU) 1 (Snellen chart), normal slit lamp examination and pupillary reflexes, normal intraocular pressure (IOP) and fundus aspect. Diplopia tests revealed a horizontal diplopia, exacerbated in left gaze. Sixth nerve palsy suspicion was raised and the patient was directed to the neurology department. Following magnetic resonance imaging, with angiographic sequence, a complex intracerebral vascular malformation that interacted with the cranial nerves and determined horizontal diplopia, was found. For a correct diagnosis, we needed a good collaboration between various medical specialties, especially ophthalmology and neurology, because patients with diplopia often present for the first time at the ophthalmologist. Abbreviations: BCVA = best corrected visual acuity, IOP = intraocular pressure, LE = left eye, RE = right eye.