The Southwest Oncology Group conducted a study of acute lymphoblastic leukemia (ALL) in adults over a 5-year period, testing the utility of the L-10M regimen initially described by the group from Memorial Sloan-Kettering Cancer Center. One hundred sixty-eight eligible patients were treated with this intensive combination chemotherapy regimen. One hundred fifteen (68%) achieved complete remission. With the current median follow-up time of 34.5 months, the median durations of remission, relapse-free survival, and overall survival were 22.9, 20.9, and 17.7 months, respectively. Only 35% of the patients over 50 years of age achieved a complete remission. Age was a significant prognostic factor for complete response, survival, relapse-free survival, and remission duration. In addition, a low initial WBC count was found to have a statistically significant association with longer remission duration. Responders between the ages of 20 and 49 years with WBC counts of less than 15,000 appear to have an exceptionally good prognosis.