OBJECTIVE Primary gastric extramedullary plasmacytoma is an extremely rare condition and there is scant information in the literature concerning its natural history or therapy. There have been anecdotal reports of surgical resection, with or without Helicobacter pylori eradication, but there are no useful reports of the role of radiotherapy. We report the clinicopathologic outcome of radical radiotherapy as a primary treatment modality. METHODS We identified two patients with biopsy-proven primary gastric extramedullary plasmacytoma. Routine staging investigations were performed and H. pylori status was determined. Radical radiotherapy to 41.4 Gy in 23 fractions was delivered using conformal techniques. The target volume was the stomach with a 1-cm margin. Prophylactic anti-emetic was administered prior to each fraction. Post-treatment endoscopies and biopsies were performed at 3-monthly intervals to assess clinicopathological response. Treatment-related toxicities were documented. RESULTS Both patients achieved durable (>12 months) pathologically confirmed complete remissions without significant toxicities. CONCLUSIONS Radical radiotherapy offers the potential for cure and organ preservation with low toxicity. It should be considered a favourable alternative to surgery in the management of this rare disease entity.