Abstract: Objective :To analyze the clinical characteri-stics and treatment result in patients with primary mediastinal large B-cell lymphoma (PMLBL). Methods :The authors reviewed the data of 34(PMLBL) patients who were admitted in Cancer Hospital,Chinese Academy Medical Science,Beijing,from July 1985 to June 2001,to evaluate the influence of clinical characteristics and treatment modality on survival. Results :Limited stage disease(I/II) was present in 79.4% of the patients,with superior vena cava syndrome 50% and contiguous infiltration 47.1%.29 of 34 patients were treated with chemotherapy plus radiotherapy,5 of 34 patients with chemotherapy alone.9 of 34 patients were treated with autologous peripheral blood stem cell transplantation (APBSCT).At median follow-up of 69 (range 18-211) months,5-year and 10-year overal l survival were 58.9% and 54.4%.5-year and 10 year disease free survival were 47.8% and 41.0%.The survival for APBSCT was better than conventional chemotherapy and radiotherapy,but the outcome had not significant difference (P>0.05).The survival for CR and bulky disease wer e significantly better than those of PR and or S+P and without bulky disease (P<0.O5). Conclusion :PMLBL is an aggressive NHL with cliniopathologic distinct.The main treatment modality for PMLBL was chemotherapy.The patients with poor prognostic factors can be considered to treat with APBSCT,but the optimal treatment modality for PMLBL 15 necessary to adopt prospective randomized trial.