We sought to investigate the clinical characteristics and pathologic features and survival outcome of patients with diffuse large B-cell lymphoma (DLBCL) arising in nodular lymphocyte predominant Hodgkin's disease (NLPHL), since controversy regarding their prognosis exists in the literature. Twenty-one patients with DLBCL arising either concurrently with (n = 7) or subsequent to (n = 14) a diagnosis of NLPHL were identified in the Nebraska Lymphoma Study Group Registry. The clinical and pathologic features of the cases were evaluated, and survival analysis was performed from the time of diagnosis of DLBCL. The median time to the development of DLBCL in those with prior NLPHL was only one year (range, 0.5-24 years). The median age of the patients at the time of diagnosis of DLBCL was 46 years (range, 18-72 years) and the male to female ratio was 17:4. Ten patients presented with nodal DLBCL only, six patients presented with both nodal and extranodal involvement, and five patients presented with only extranodal DLBCL. Eleven patients had limited stage (I/II) disease and 10 had advanced stage (III/IV) disease. The median overall survival (OS) and failure-free survival (FFS) of the entire group was 35 months and 11 months, respectively, and the predicted five-year OS and FFS was 31 and 18%, respectively. There were no significant differences in the survival outcomes between patients with DLBCL arising in NLPHL and age- and sex- matched patients with de novo DLBCL. In conclusion, our findings suggest that patients with DLBCL arising in NLPHL have a prognosis similar to those with de novo DLBCL and should be treated aggressively.