The study evaluates the efficacy and tolerability of a risk- and subtype-adapted chemotherapy over one year, followed by randomized either intensified or conventional maintenance therapy. It includes a distinct protocol for the subgroup 'mature B-ALL',

Inclusion Criteria:

• Acute Lymphocytic Leukemia
• Age 15 - 65 years

Exclusion Criteria:

• Serious secondary diseases which may compromise intensified chemotherapeutical treatment
• Serious psychiatric diseases, which may compromise compliance with therapy
• HIV-1 or HIV-2 Infection
• Pretreatment > 2 weeks or chemotherapy other than Vincristine and Steroids
• Patients without central diagnosis who cannot be allocated to a risk group