ABSTRACTAcute lymphoblastic leukemia (ALL) is the most common childhood cancer. Although curable, approximately 20% of patients relapse. In an effort to detect relapse earlier, our institution performed surveillance bone marrow (BM) and cerebrospinal fluid (CSF) evaluations every 3 months from the end of therapy to 1 year off. This study retrospectively reviewed all patients with B-cell ALL (B-ALL) from September 2005 to September 2010 to determine the benefit and cost of these procedures. Forty-one patients completed therapy and had 190 BMs and 190 lumbar punctures (LPs) performed. Four of 41 patients (9.8%) experienced a relapse. Relapse was detected in only 1 patient by routine BM evaluation (0.5%). Zero LPs were positive. The professional fees for the procedures were $8,738/patient. Therefore, off-therapy BM and CSF evaluations are not effective at detecting relapse and are expensive. Our institution has abandoned off-therapy surveillance for ALL.