ABSTRACT. Magalhães G.M., Santilli J., Calazans S.G., Nishimura L.T., Cerejo S.A. & Dias F.G.G. [Primary fibrosarcoma im small intestine of dog - Case report.] Fibrossarcoma primário em intestino delgado de cão - Relato de caso. Revista Brasileira de Medicina Veterinária, 37(2):145-148, 2015. Programa de Pós-Graduação em Medicina Veterinária de Pequenos Animais, Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201, Cx postal 82, Parque Universitá- rio, Franca, SP 14404-600, Brasil. E-mail: email@example.com Intestinal neoplasms are uncommon in dogs, and among the most frequently diagnosed are smooth muscle, lymphomas and carcinomas. The fibrosarcoma is extremely rare in the intestine of animals of this species therefore, little is known about the macroscopic and behavior of this tumor. Given this unusual intestinal disease in dogs, the present study aimed to report a case of intestinal fibrosarcoma in a poodle breed dog, 15 years old, with no apparent clinical signs. The mass was pedunculated, whitish and firm consistency. The diagnosis was made by histopathology. After four months of surgical excision, there was no recurrence and metastasis. We conclude that the intestinal fibrosarcoma has low aggressiveness, are rare and can present macroscopic pediculated.