This study reports a rare case of maxillary osteomyelitis in a horse caused by Halicephalobus gingivalis. The horse presented inflammation and pain in the region of the right facial crest and the radiographs detected osteolysis and widening of the facial crest. The biopsy revealed a granulomatous inflammation and a large amount of parasite larvae. The horse was treated with ivermectin but it developed uveitis and renal insufficiency 2.5 months later and was euthanised. The anatomopathological study found multiple parasitic granulomas in the kidneys and uveal tract. H. gingivalis is an infrequent infection in horses and people, and it has a worldwide distribution. To the best of our knowledge this is the first report of H. gingivalis infection in an equid to be diagnosed in Spain.