Fourteen patients with localized orbital mucosa-associated lymphoid tissue lymphoma diagnosed between 1998 and 2005 were reviewed. Five patients were males and 9 were females, with a mean age of 58 years. In 8 patients, the disease arose from the conjunctiva, and in 6 patients, it originated from the retrobulbar space. Patients were treated with radiotherapy alone at a dose range from 30 to 54 Gy. All patients with conjunctival lymphoma achieved complete remission (CR). Four patients with retrobulbar lymphoma obtained CR, and unconfirmed CR (CRu) was observed in 2 cases. Orbital extraconal lymphoma disappeared. However, intraconal cord-like tumor and mass involving the medial extraocular muscle remained with the absence of regrowth over the long term. There have been very few reports discussing the histology of residual mass after radiotherapy. Residual mass was suggested to be reactive lymphoid hyperplasia. As a dose of more than 40 Gy induced dry eye syndrome or cataract, the dose must not exceed 40 Gy in order to achieve safe treatment of orbital mucosa-associated lymphoid tissue lymphoma.