Ophthalmomyiasis interna posterior (OIP) means infection of the posterior part of the eye with the larvae of flies. Few cases have been reported in which the larvae have been removed from the eye and the visual acuity preserved. We report four cases of OIP with living larva in the vitreous cavity. The larvae produced severe uveitis and were removed alive with vitrectomy and a procedure for removing foreign bodies. They were identified as first-stage reindeer warble fly larvae (Oedemagena tarandi). We also observed dead larva in the vitreous cavity of a patient who suffered severe uveitis in 1943, and this eye survived with normal visual acuity. Another patient had a blind eye enucleated and the remnants of a larva were found inside the eye. All patients live in Scandinavia.