Despite advances in treatment, including the introduction of rituximab, survival after diffuse large B-cell lymphoma (DLBCL) remains heterogeneous. However, no studies have considered the association between neighborhood socioeconomic status (SES) and race/ethnicity on DLBCL mortality before (1988-2000) and after (2001-2009) the introduction of rituximab. We studied all 33,032 DLBCL patients diagnosed between 1988-2009 in California for vital status through December 31, 2010. Patients diagnosed from 2001 to 2009 vs 1988 to 2000 had significantly decreased overall and DLBCL-specific mortality. However, those living in lower SES neighborhoods had 34% (95% confidence interval [CI], 27%-40%) and 24% (95% CI, 16%-32%) higher mortality rate from all causes and lymphoma, respectively, than patients in higher SES neighborhoods. The magnitude of mortality disparities by neighborhood SES was more marked in younger (<65 years) than in older patients (≥65 years), in married than nonmarried patients, and after 2000. We concluded that patients living in low SES neighborhoods had substantially worse survival after DLBCL, and this disparity was striking in younger (ie, not eligible for Medicare-aged) patients, married patients, and after the introduction of rituximab. These disparities suggest there are barriers, including inadequate insurance coverage with additional financial burden, to effective treatment among socioeconomically disadvantaged patients.