CCG-2961 incorporated 3 new agents, idarubicin, fludarabine and interleukin-2, into a phase 3 AML trial using intensive-timing remission induction/consolidation and related donor marrow transplantation or high-dose cytarabine intensification. Among 901 patients under age 21 years, 5-year survival was 52%, and event-free survival was 42%. Survival improved from 44% between 1996 and 1998 to 58% between 2000 and 2002 (P = .005), and treatment-related mortality declined from 19% to 12% (P = .025). Partial replacement of daunomycin with idarubicin in the 5-drug induction combination achieved a remission rate of 88%, similar to historical controls. Postremission survival was 56% in patients randomized to either 5-drug reinduction or fludarabine/cytarabine/idarubicin. For patients with or without a related donor, respective 5-year disease-free survival was 61% and 50% (P = .021); respective survival was 68% and 62% (P = .425). Donor availability conferred no benefit on those with inv(16) or t(8;21) cytogenetics. After cytarabine intensification, patients randomized to interleukin-2 or none experienced similar outcomes. Factors predictive of inferior survival were age more than 16 years, non-white ethnicity, absence of related donor, obesity, white blood cell count more than 100 000 × 109/L, -7/7q-, -5/5q-, and/or complex karyotype. No new agent improved outcomes; experience may have contributed to better results time.