Background/Aim: Feline mammary carcinomas (FMCs) are characterized by poor prognosis and little progress has been made in extending patient survival. The aim of the study was to compare overall survival periods of FMCs submitted to different treatment protocols, including surgery and adjuvant chemotherapy. Materials and Methods: Analysis of conventional surgical excision alone or in association with adjuvant chemotherapy with carboplatin in sixteen cats diagnosed with stage III and grade II or III FMCs was performed. Results: Patients treated with surgery and chemotherapy presented a longer overall survival (OS) than those treated only with surgery, however, no statistical difference was observed when comparing both treatments (p=0.883). Conclusion: Therapeutic benefit of carboplatin remains invalidated for FMCs and further investigation regarding adjuvant therapies are warranted. Surgery remains as the gold treatment in FMCs.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Sao Paulo State Univ FCAV UNESP, Sch Agr & Vet Sci, Postgrad Program Vet Med, Jaboticabal, BrazilFed Univ Minas Gerais UFMG, Biol Sci Inst ICB, Dept Gen Pathol, Lab Comparat Pathol, Belo Horizonte, MG, BrazilFed Univ Minas Gerais UFMG, Sch Vet, Vet Hosp, Dept Vet Clin & Surg, Belo Horizonte, MG, BrazilSao Paulo State Univ FCAV UNESP, Sch Agr & Vet Sci, Postgrad Program Vet Med, Jaboticabal, Brazil