The Dutch Childhood Leukemia Study Group (DCLSG) performed a phase III study-Study (ALL) V-to evaluate the effectiveness of rubidomycin in induction therapy with vincristine, prednisone, and L-asparaginase for children (0-15 years) with standard risk acute lymphoblastic leukemia (ALL) (white blood cell [WBC] counts less than 50.10(9)/L, absence of mediastinal mass, and/or cerebromeningeal leukemia). Furthermore, the influence of initial patient and disease characteristics on the outcome was analyzed. Between May 1979 and December 1982, 240 patients entered the study and were randomized into two groups: group A (n = 122) received induction treatment with vincristine (VCR), prednisone (Pred), and L-asparaginase (L-Asp); for group B (n = 118), induction therapy consisted of VCR, Pred, L-Asp, and rubidomycin (Rub). All patients subsequently underwent cranial irradiation (doses adjusted to age) in combination with intrathecal methotrexate; maintenance therapy of 6-mercaptopurine and methotrexate for 5 weeks followed by vincristine and prednisone for 2 weeks was given for 24 months. The complete remission (CR) rate was similar in both groups (94.5%). Event-free survival (EFS) 5 years after diagnosis was higher in group B (62.5 +/- 4.5%) than in group A (54.7 +/- 4.5%), although the difference is not significant (p = 0.20). A high initial WBC (greater than or equal to 10.10(9)/L), age (greater than or equal to 10 years), a low platelet count (less than 100.10(9)/L), and a positive acid phosphatase reaction of the leukemic cells were unfavorable prognostic factors (p less than 0.05). Sex, French-American-British (FAB) classification group, immunophenotype, and treatment in specialized centers did not have a significant impact on event-free survival.