This case report describes an 11 yr old spayed female German shepherd dog weighing 42 kg that presented with intermittent epistaxis from the left nostril. A nonulcerated pale irregular polypoid mass was visualized within the left nares. Computed tomography revealed a pedunculated mass arising from the ventrolateral nasal mucosal of the left nasal cavity with no evidence of involvement or invasion of adjacent soft tissues or bony structures. Histological and immunohistochemical examination of rhinoscopic biopsies returned a diagnosis of an angioleiomyosarcoma. The mass was excised using a modified lateral approach to the nasal cavity. Fulguration of the wound bed was performed. Clean surgical margins were identified on histopathology. The dog remained clinically free of recurrence 28 mo postsurgically. Angioleiomyosarcomas are rare tumors originating from the smooth muscle cells of blood vessel walls and are included in the spectrum of perivascular wall tumor, a subgroup of soft-tissue sarcomas.