Hemimaxillectomy was performed in 69 dogs for the treatment of benign or malignant maxillary tumors. Eighteen dogs with ameloblastomas had a median disease-free interval of 21.5 months (range, 1 to 76 months), with a 72% 1-year survival time. There was recurrence in three dogs, with metastasis after malignant transformation in one of them. Based on calculated survival curves, seven dogs with squamous cell carcinoma had a median survival time of 19.2 months (range, 2 to 24 months), with a 57% 1-year survival time. There was local recurrence in two dogs. Twenty-three dogs with melanoma had a median survival time of 9.1 months (range, 1 to 46 months), and a 27% 1-year survival time. Twelve dogs died or were euthanatized because of recurrence or metastases. Fifteen dogs with fibrosarcoma had a median survival time of 12.2 months. Eight dogs died or were euthanatized because of recurrence or metastases. Six dogs with osteosarcoma had a median survival time of 4.6 months (range, 1 to 12.5 months), with a 17% 1-year survival time. Five dogs died or were euthanatized for recurrence or metastases. Tumor size or location and type of partial maxillectomy performed did not affect survival.