Objective: To investigate the relationship between MALT1 mRNA expression in extranodal B cell lymphoma and the pathogenesis of MALToma and DLBCL, and to explore the effect of MALT1 mRNA expression on the clinicopatho-serve the expression of Bcl-2 and Ki-67 in 106 samples of extranodal B cell lymphoma.The mRNA of MALT1 was detected by RT-PCR.Clinicopathological data were reviewed.Follow-up and statistical analysis were performed.Results: Expression of MALT1 mRNA was statistically different between the cases with lymph node metastasis and those without lymph node mestastasis, and between staging Ⅰ-Ⅱ cases and stage Ⅲ-Ⅳ cases, The expression of MALT1 mRNA in cases with posi-tive expression of MALToma, DLBCL, and Bcl-2 was higher than in those without expression of the three indices (P<0.05).However, no significant difference was found in MALT1 mRNA expression between cases with Ki-67≥30% and those with Ki-67<30% (P>0.05).MALT1 mRNA-positive cases showed a worse survival status than MALT1 mRNA-negative cases (P<0.05).Conclusion: Expression of MALT1 gene is different between MALToma and DLBCL.Inhibition of apoptosis by Bcl-2 overexpression caused by activation of NF-κB may lead to the pathogenesis of MALToma and DLBCL.The expression of MALT1 mRNA is associated with the types of lymphoma, involvement of lymph node, stage of lymphoma, and patient sur-vival.The expression of MALT1 gene may be associated with poor prognosis of MALToma and DLBCL.