BACKGROUNDRecurrence of acute lymphoblastic leukemia (ALL) in the central nervous system (CNS) in adults is considered a poor prognostic feature. Few reports have analyzed this issue. The objective of this study was to analyze the experience with CNS recurrence in adult patients with ALL.METHODSBetween December 1982 and April 2000, the records of 527 consecutive, newly diagnosed patients with ALL who were treated at the M. D. Anderson Cancer Center were reviewed. Patients were treated with one of two published regimens: vincristine, doxorubicin, and dexamethasone (VAD; n = 237 patients) or hyperfractionated cyclophosphamide plus VAD (hyper‐CVAD) (n = 290 patients). Among 439 patients (83%) who achieved complete remission (CR), 32 patients (7%) had a CNS recurrence. All patients had received CNS prophylaxis tailored to the risk of CNS recurrence with systemic chemotherapy with or without intrathecal (IT) chemotherapy; none received cranial radiotherapy for prophylaxis. The records of these patients were reviewed.RESULTSThe median age at the time of diagnosis was 33 years. The median CR duration prior to CNS recurrence was 36 weeks (range, 2–185 weeks). Three groups were identified: 1) patients with an isolated CNS recurrence (n = 17 patients), 2) patients with CNS recurrences after bone marrow (BM) recurrence (n = 8 patients), and 3) patients with simultaneous CNS and BM recurrences (n = 7 patients). IT chemotherapy was effective in achieving a CNS CR in 30 patients (94%), but 10 patients (31%) had a second CNS recurrence. The median survival from CNS recurrence was 6 months; 28% of patients were alive at 1 year, and 6% of patients were alive at 4 years.CONCLUSIONSAdults with ALL and CNS recurrences have a poor prognosis despite effective IT chemotherapy. Future studies should investigate better approaches in the treatment of these patients to improve their long‐term survival. Effective CNS prophylaxis remains the single best approach for treating patients with CNS leukemia. Cancer 2002;94:773–9. © 2002 American Cancer Society.DOI 10.1002/cncr.10265