Forty-four children aged 3-13 years with Murphy stage III B cell non-Hodgkin's lymphoma were treated between May 1986 and December 1989. All have been followed up for at least 12 months. The primary site was the abdomen in 37 children, 24 of whom had involvement of other organs or nodal disease outside the abdomen. Twenty-eight received a standard dose regimen (regimen 1) and 16 had a more intensive regimen (regimen 2--MACHO). Fourteen patients (87%) who received MACHO had extensive multi-organ disease compared to 15 (53%) on regimen 1. Most of the latter had only pleural effusions. Thirty-four children are alive relapse free and considering the early relapse pattern in this disease are probably cured (actuarial event free survival = 76%). There has been one relapse (6%) after MACHO, but three toxic deaths. Six patients (21%) on the less intensive regimen have relapsed. Morbidity was high in terms of infection and need for haematological support and hospitalisation in the one third of children electively given the more intensive regimen. It is concluded that the vast majority of children with stage III disease who have disease limited to lymph nodes are curable with a moderately intensive regimen. Those with multiorgan involvement probably require more intensive treatment. It is therefore of importance to clarify prognostic factors in these patients to determine who can be cured with a less intensive regimen and who requires further dose intensification.