The first case of primary gastric lymphoma associated with Behçet's disease is reported. A 43-year-old woman, who had been treated for Behçet's disease for 15 years, was diagnosed as low-grade and small lymphocytic malignant lymphoma of the stomach. Although the patient had been treated for Behçet's disease, chemotherapy was performed and a complete remission of gastric lymphoma was achieved. The literature regarding the association of malignant diseases with Behçet's disease is briefly reviewed.