Background. Mucosa-associated lymphoid tissue lymphoma (MALToma) is a Helicobacterpylori-related tumor of B-cell origin, the malignant potential for which remains to be defined in immunosuppressed patients. Methods. Review of the Israel Penn International Transplant Tumor Registry identified six cases of gastric MALToma. Patient demographics, management, and outcomes were compared and published literature was reviewed. Results. MALToma developed in six transplant recipients (three kidney, two heart, one kidney-pancreas). All were treated with immunosuppression minimization and therapy for H. pylori, resulting in disease regression in five patients. One patient developed progression to high-grade MALToma despite documented H. pylori eradication, required surgery and chemotherapy, and died, with significant disease at autopsy. Conclusions. Treatment of MALToma with immunosuppression minimization and anti-H, pylori therapy results in a majority of patients becoming disease free. Observation of malignant degeneration into an aggressive, high-grade lymphoma in one patient indicates the malignant potential. Diligent follow-up of these patients with endoscopy and biopsy is therefore indicated.