SUMMARY This paper describes two cases of gastric leiomyoblastoma (bizarre smooth muscle tumour), one of them having evidence of metastases. Both patients remain well after seven years and three and a half years respectively. The literature is reviewed, and the clinical features, diagnosis, and treatment are discussed. The histological appearances are described in detail and an attempt is made to assess the criteria for the diagnosis of malignancy.Smooth muscle tumours are the commonest nonepithelial tumours of the stomach, and the occurrence of both benign and malignant forms is higher in this organ than elsewhere in the gastrointestinal tract. They form 2.47% of all gastric tumours (Skandalakis, Gray, and Shepherd, 1960