In localized neuroblastoma, the identification of patients requiring intensive treatment is still difficult. We retrospectively analyzed data of 280 single copy MYCN stage 2 and 3 neuroblastoma patients with gross residual tumor after initial surgery. The 3-year-event free survival of the total group was 83+/-2%, and 3-year-overall survival was 92+/-2%. Patients < or=1.5 years had a better outcome than older children. Deletions/imbalances of chromosome 1p were found in 9/90 patients and were associated with a higher event rate but not with a higher death rate. Aberrations of chromosome 11q in 14/91 patients were correlated with a higher event and death rate. Multivariate analysis identified 1p aberrations as important for event free survival and 11q aberrations for overall survival.