Less is known about the clinical features and treatment outcome in pediatric large cell non-Hodgkin lymphoma (NHL) than the lymphoblastic and small noncleaved cell subtypes of NHL. To characterize presenting features and assess possible risk factors associated with this diagnosis, we analyzed data for 91 patients treated on a succession of multiagent regimens from 1975 to 1990. Five-year event-free survival (EFS) (+/- SE) was related to disease extent (St Jude system): stage I (n = 24), 95% +/- 5%; stage II (n = 20), 84% +/- 9%; stage III (n = 38), 50% +/- 10%; and stage IV (n = 9), 22% +/- 11%. Advanced stage disease, age < or = 5 years and serum LDH > 500 U/l were associated with poorer EFS in the univariate model (p < 0.001, 0.005, and 0.002, respectively). In the multivariate model, advanced stage and age retained prognostic significance (p = 0.001 and 0.02, respectively), but LDH did not. Among limited stage cases, age < or = 5 years was the only adverse risk feature (p = 0.016); treatment era (pre- vs. post-1979) was the only significant feature in patients with advanced disease (p = 0.004). Intrathoracic primaries were associated with a better outcome than other sites among the 38 stage III patients (p = 0.005). Only one of eight patients with bone marrow disease remains failure-free. The excellent results for limited stage pediatric large cell NHL permit consideration of treatment modifications to decrease toxicity; for cases with advanced disease, especially those with bone marrow involvement, novel therapeutic approaches are clearly needed.