In a retrospective review of all patients who admitted our hospital between January 1992 and December 2006, we identified 9 with anterior mediastinal malignant lymphoma. They represented 6.8% of the 133 patients with mediastinal tumor. Histology revealed 3 cases of primary mediastinal large B-cell lymphoma, 2 of Hodgkin lymphoma, 2 of precursor T-lymphoblastic lymphoma and 2 of thymic extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) lymphoma. Careful attention should be paid to the relatively high incidence of malignant lymphoma in the anterior mediastinal tumors. It is highly important to differentiate of malignant lymphoma from other diseases that shape anterior mediastinal tumor to avoid unnecessary operation. Early and accurate diagnosis of these tumors is also important because some of these patients require immediate treatment by hematology specialists.