Background Primary non-Hodgkin’s lymphoma in lung is very rare,and the most common among them ismucosa-associated lymphoid tissue lymphoma(MALToma),whose clinical features and laboratory characteristics arepoorly defined,making diagnosis difficult.The purpose of this study was to study the diagnosis and treatment ofpulmonary MALToma.Methods The clinical data of 12 patients treated for MALToma between August 1992 and December 2005 wereanalyzed.Results No specific symptoms or signs,or results of bronchoscopy,ultrasonagraphy or bone marrow examinationcould be found in the 12 patients.Only radiography was useful in diagnosis,though the final diagnosis of all the patientswas based on histology and immunohistochemistry.Two patients also had gastric MALToma.Operations were performedon 6 patients,including 5 radical operations and 1 partial resection:4 patients also received adjuvant chemotherapy.Onepatient experienced recurrence 152 months after the operation,while the other 5 patients have survived disease-free.Four patients were treated with chemotherapy alone,two of whom experienced complete remission and the others partialremission.The final 2 patients received no treatment and had survived for 7 and 27 months respectively.All the patientswere still alive at the most recent follow-up,7 to 160 months(mean 71.3 months).Conclusions Except radiography,no specific clinical manifestations could be identified for pulmonary MALToma.Thefinal diagnosis should be based on histology and immunohistochemistry.Several treatment methods can be used toachieve good outcomes. Background Primary non-Hodgkin’s lymphoma in lung is very rare, and the most common among them is mucosa-associated lymphoid tissue lymphoma (MALToma), whose clinical features and laboratory characteristics arepoorly defined, making diagnosis difficult. The purpose of this study was to study the diagnosis and treatment of pulmonary MALToma. Methods The clinical data of 12 patients treated for MALToma between August 1992 and December 2005 were analyzed. Results of specific symptoms or signs, or results of bronchoscopy, ultrasonagraphy or bone marrow examination can found in the 12 patients. Only radiography was useful in diagnosis, though the final diagnosis of all the patients is based on histology and immunohistochemistry. Two patients also had gastric MALToma. Operations were performed on 6 patients, including 5 radical operations and 1 partial resection: 4 patients also received adjuvant chemotherapy. Oxpatient experienced recurrence 152 months after the operation, while the other 5 patients have s urvived disease-free.Four patients were treated with chemotherapy alone, two of whom experienced complete remission and the others partialremission. the final 2 patients received no treatment and had survived for 7 and 27 months respectively. All the patientswe still still at the most recent follow-up, 7 to 160 months (mean 71.3 months) .Conclusions Except radiography, no specific clinical manifestations could be identified for pulmonary MALToma. The final diagnosis should be based on histology and immunohistochemistry. Treatment treatment can be used toachieve good outcomes.