<p><b>OBJECTIVE</b>To explore the prognostic impact of bone marrow involvement (BMI) and therapy in diffuse large B cell lymphoma (DLBCL).</p><p><b>METHODS</b>The clinical characteristics and prognosis of 83 DLBCL patients with or without BMI were retrospectively analyzed. The treatment outcome of standard CHOP regimen (CHOP group), intensive-dose regimen (intensive-dose group) and rituximab combined therapy (rituximab group) were compared.</p><p><b>RESULTS</b>The adverse prognostic factors including LDH elevation, ECOG score > or =2, higher IPI and aaIPI score, B symptom, hepatomegaly, splenomegaly, hemoglobin <110 g/L, platelet <100 x 10(9)/L and serum albumin <35 g/L were more prevalent in DLBCL patients with BMI than in those without BMI. Multivariate analysis showed that BMI was an independent prognostic factor of DLBCL. The 3-year OS and PFS rates in rituximab group were 78.1% and 64.3%, respectively, being statistically higher than that in CHOP group (23.6% and 21.8% respectively, P = 0.000 for both) and in intensive-dose group (33.3% and 25.7% respectively, P = 0.002 and 0.001, respectively). But no difference between the latter two groups (P = 0.411 and 0.694, respectively). For the patients with BMI, the 3-years OS and PFS in rituximab group (57.1% and 57.1%) were statistically higher than that in CHOP group (13.9% and 14.1%) and intensive-dose group (29.5% and 16.8%) (P = 0.029 and 0.012 respectively), respectively and also no difference in the latter two groups (P = 0.226 and 0.376 respectively). In the rituximab group, the 3-years OS and PFS were 86.7% and 67.3% respectively in patients without BMI, being higher than that in patients with BMI (57.1% and 57.1%), but the difference was not statistically significant (P = 0.645 and 0.965 respectively).</p><p><b>CONCLUSION</b>BMI is a negative independent prognostic factors of DLBCL patients. The rituximab combined chemotherapy can significantly improve the therapeutic effect of the DLBCL, and relieve the negative impact of BMI.</p>