A case of a canine oral eosinophilic granuloma in a 14-year-old female crossbred is described. The dog was presented with a history of ptyalism, halitosis, local pain, decreased appetite, and blood staining noted on food and water bowls. Clinical, hematologic, and biochemical examinations, abdominal ultrasonography, and 3-view chest radiographs were performed, and no metastases were found. Histopathologic examination of two 6 mm punch biopsies from the oral lesion revealed the presence of eosinophilic granulomatous lesions in the submucosa. After treatment with corticosteroids and wide spectrum antibiotics no significant changes in clinical signs and lesion size were observed. Electrochemotherapy (ECT), a novel tumor treatment routinely used for cutaneous and subcutaneous tumors in human patients in the European Union since 2006, was used to treat the eosinophilic granuloma. The procedure was performed under general anesthesia, followed by intravenous administration of bleomycin. Six weeks after treatment a complete response with disappearance of the mass and improvement of clinical signs were observed.