Crenosoma striatum is a species of parasitic nematodes from the family Crenosomatidae responsible for pathologic lung lesions in the hedgehog (Erinaceus europaeus). Infection with C. striatum can cause weight loss, dry cough, and bronchitis. In the present study, hedgehogs killed by road accidents, or trapped and found dead on farms in different parts of Mazandaran province (Iran), were transferred to the laboratory. After dissection, parasite samples collected from the lung were placed into 70% alcohol. After clarification with lactophenol and subsequent staining, the nematodes were identified as C. striatum according to previously published guidelines. For histopathologic examination, lung samples were collected. The tissues were fixed and following routine processing, sections were stained with hematoxylin and eosin. Microscopic diagnoses included hyperemia, eosinophilic bronchointerstitial pneumonia, thickening of the interstitium, and eosinophilic microabscesses in bronchial airways. Eosinophilic pneumonia was characterized by eosinophil and other mononuclear leukocyte infiltration within the lung interstitium. Crenosoma striatum can lead to mortality in hedgehogs.