ABSTRACT. Ramadinha R.R., Teixeira R.S., Bomfim P.C., Mascarenhas M.B., França T.N., Peixoto T.C., Costa S.Z.R. & Peixoto P.V. [Response of canine transmissible venereal tumor to vincristine sulfate and vinblastine sulfate chemotherapy.] Resposta do tumor venéreo transmissível canino à quimioterapia com sulfato de vincristina e vimblastina. Revista Brasileira de Medicina Veterinária 38(Supl.1):65-69, 2016. Departamento de Medicina e Cirurgia Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, Rodovia BR 465 Km 7, Seropédica, RJ 23851-970, Brasil. E-mail: email@example.com From 165 dogs, males and females, affected by the transmissible venereal tumor (TVT), 103 were submitted to therapy protocols with vincristine sulfate - VC - (0.025 mg/kg) and 62 with vinblastine sulfate - VB - (2.5 mg/m2 ). The drugs were administered intravenously once a week. From the animals treated with VC, 65 received a complete treatment and 64 (98.46%) were cured. Fifty eight dogs (89.23%) had complete regression with one to six VC injections until the total remission of the tumor. Only six dogs (9.23%) had to receive seven to ten VC applications. Thirty-eight dogs (36.89%) had their treatment abandoned after one to three VC applications, in general when presented partial involution of the neoplasia. Of those 62 treated with VB, 36 dogs had the treatment completed with total remission (100%) of the neoplasia. Thirty two animals (88.89%) needed one to six applications, while 4 dogs (11.11%) needed seven to eight doses to eliminate the tumors. It was concluded that both VC as VB are effective however, the VC should remain the drugs of choice for its low cost compared to VB, which, however, should be the drug of choice when the VC is not viable. Side effects characterized by vomiting, loss of appetite and diarrhea, as well as hematological disorders were considered mild and it do not preclude the use of both drugs.