With currently available combination chemotherapy regimens, the outcome of the patients newly diagnosed with aggressive non-Hodgkin's lymphoma (NHL) identified as 'high' and 'high-intermediate' risk groups according to the international prognostic index ( IPI) is still unsatisfactory and a more innovative therapy is urgently required to improve the survival of the patients. The purpose of this study was to compare the efficacy of rituximab given in combination with CHOP ( cyclophosphamide, doxorubicin, vincristine, prednisone) and ESHAP ( etoposide, methylprednisolone, high-dose Ara-C, cisplatin) vs CHOP-ESHAP and upfront high-dose therapy (HDT) and autologous stem cell transplantation ( ASCT) vs standard CHOP in patients aged <= 65 years old newly diagnosed with 'high' and ` high-intermediate' risk aggressive lymphoma enrolled onto two consecutive treatment trials at the institute. Between May 1995 - July 2002, 84 patients, aged 15 - 65 years old, with newly diagnosed aggressive NHL and an age-adjusted IPI of 2 or 3 were enrolled. The median age of the patients was 38 years ( range 15 - 65). The baseline demographic features, in particular the major prognostic variables, were similar between the treatment groups. Patients treated with rituximab-CHOP-ESHAP received eight cycles of rituximab ( 375 mg m(-2) on day 1 of cycles 1 - 6 and days 21 and 28 of cycle 7) plus CHOP ( day 3 of cycles 1, 3 and 5) and ESHAP ( day 3 of cycles 2, 4 and 6 and day 1 of cycle 7) at 21-day intervals. Patients enrolled onto the CHOP-ESHAP-HDT arm ( n = 23) were treated with three courses of CHOP and then switched to two or four cycles of ESHAP followed by HDT. Patients treated with CHOP alone ( n 25) were treated with the standard eight cycles of CHOP. The rate of complete remission was significantly improved with rituximab-CHOP-ESHAP compared with either CHOP-ESHAP-HDT or CHOP alone (67% compared with 44% and 36%, respectively; p = 0.043). With a median follow-up time of 53 months, the 5-year overall survival ( OS) was improved by the addition of rituximab - 61% with rituximab-CHOP-ESHAP, compared with 43% for CHOP-ESHAP-HDT and 24% for CHOP alone ( p = 0.088). Significant increases in failure-free survival (FFS) and disease-free survival (DFS) ( 61% and 96%), compared with CHOP-ESHAP-HDT (34% and 90%) and CHOP (16% and 44%; p = 0.002 and p<0.001, respectively) were observed. Compared to CHOP, rituximab-CHOP-ESHAP yielded significantly superior OS ( p = 0.014), FFS (p<0.001) and DFS ( p<0.001). The survivals, however, were not significantly different from patients treated with CHOP-ESHAP-HDT. It is concluded that rituximab-ESHAP-CHOP is superior over standard CHOP and fares comparably to upfront HDT/ASCT in previously untreated patients with aggressive lymphoma. A prospective randomized controlled trial is warranted to confirm these results.