ABSTRACT. da Silva L.S., Santin A.P.I., da Silva J.A., de Freitas S.L.R. & da Silva L.A.F. [Dianostic and treatment of hemangisarcoma in a female dog’s ovary - Case report.] Diagnóstico e tratamento de hemangiossarcoma em ovário de cadela - Relato de caso. Revista Brasileira de Medicina Veterinária, 37(2):123-126, 2015. Patologia Clínica Cirúrgica, Hospital Veterinário, Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Campus II Samambaia, Caixa Postal 131, Goiânia, GO 74001-970, Brasil. E-mail: firstname.lastname@example.org Increase in life expectation in dogs can be attributed to therapeutics advances in Veterinary Medicine. Despite the benefits, longevity makes these animals more susceptible to a variety of diseases like cancer. This paper reports a hemangiosarcoma, weighting 6,5Kg, on the ovary of a Pit Bull, nine years old, female dog, emphasizing diagnostics and treatment. Surgical intervention and post-operative care were performed immediately after complementary exams results were evaluated. The animal was observed during 12 months after surgery in order to evaluate the clinical conditions and the possibility of recurrence. Surgical treatment was important to assist the diagnosis. Recurrence was not observed during the evaluation period. Also, surgical treatment associated with chemotherapy was not necessary.