Objective To study the CT and MRI radiological features of lymphoma in the third ventricle and improve the understanding and diagnosis of it. Methods CT and MRI manifestations of 5 patients with lymphoma in the third ventricle which proved by surgery and pathology were analyzed retrospectively. The follow findings of the lesions were evaluated, including location, morphology, size, margin, peritumoral edema, MRI plain scan, enchancement pattern and 1 H-MRS. Results A1l lesions appeared as round or oval isodensitiy or hyperdensity solid masses on CT scan, isointensity or hypointensity on T1WI, iso intensity or hyper intensity on T2WI, The tumors showed homogeneous marked enhancement on contrast-enhanced scan and manifestated "Fist clenching sign", "close angle sigh", " notch sign" and "open-ring sign". NAA peak reduced, Cho peak increased and Lip peak increased significantly on 1 H-MRS.Pathologically,the tumor cells were diffusely distributed and same sized with less cytoplasm and larged nucleus， calcification, hemorrhage or piece of necrosis were rare. Conclusion Lymphoma of the third ventricle has certain imaging features. The diagnosis of Lymphoma of the third ventricle is limited by imaging alone. Clinical data, histomorphology and immunohistochemistry are still needed to confirm the diagnosis..