Purpose <p><i>Eucoleus aerophilus</i> (syn. <i>Capillaria aerophila</i>) (Nematoda: Capillariidae) is a common endoparasite of free-ranging canids. In zoological gardens, reports on <i>E. aerophilus</i>-infections are scarce. We here present a case series of <i>E. aerophilus</i> infections in zoo-held arctic foxes with the aim to provide assistance for zoo veterinarians for future cases.</p> Methods <p>A total of five zoo-born and -housed arctic foxes (<i>Vulpes lagopus</i>) were presented with coughing periods and strong phlegm, four of them showing rapid deteriorations at different time points including dyspnoea leading to death. Coproscopical analysis of pooled and individual faecal samples and necropsies were performed.</p> Results <p>Faecal analysis showed shedding of typical capillariid eggs, which corroborated the suspicion of respiratory capillariosis. Multiple attempts of deworming using different anthelmintic treatment protocols (fenbendazole; milbemycinoxime and praziquantel; ivermectin; levamisole; selamectin; moxidectin and imidacloprid) did neither result in negative egg shedding periods nor in improvement of clinical symptoms. A regime performed with fenbendazole (100&#xa0;mg/kg bodyweight per os over 14&#xa0;days) resulted in cessation of egg shedding. At necropsy of four animals, multifocal chronical granulomatous pneumonia was diagnosed, associated with a massive infection with adult nematodes detected in trachea, bronchi and bronchioles and bacterial infections. Morphological analysis of extracted nematodes identified <i>E. aerophilus</i>, which was confirmed by molecular analysis based on the 18S rRNA gene.</p> Conclusion <p>We here show clinical and necropsy data and morphological and molecular worm identifications and call for further parasitological research in ex&#xa0;situ populations of arctic foxes to assess the impact of parasites on this species.</p>