Neoplasms of the canine stomach are uncommon: in reports on neoplasm occurrence in domestic animals in Poland in 1957-1993 there was no mention of gastric tumors. However, in the past gear, two cases of neoplasms of the stomach were diagnosed in the Department of Pathology of the Agricultural University in Wroclaw. The first case was in a ten-year-old mongrel bitch, in which diffuse thickening of the lateral wall of the atrum pyloricum was observed. There was no ulceration, merely flattening of the gastric folds. The tumor constituted an inconsistent microscopic structure which in WHO classification was determined as adenocarcinoma of mixed type (tubular-mucionous-,,signet ring" cell- undifferenciated), but according to Patnaik it could be classified as intermediate adenocarcinoma (intestinal diffuse). A resection of 1/5 of the stomach wall was done, but due to persistent vomitting, anorexia and progresive emaciation, the dog was euthanasied 10 days after the operation. The second case was a 15-year-old male mongrel. In the course of diagnostic laparotomy a neoplastic tumour 4 cm in diameter was found in the Lateral wall of the pylorus. Histopathological examination revealed the typical structure of leiomyosarcoma. A wide spectrum of techniques are recomended in the diagnosis of the stomach neoplasms, such as RTG, USG and endoscopy, supported with the biopsy of about 10 specimens, and intraoperation histopathological examination. Surgery and chemotherapy are used in the treatment; however survival time is usually short.