Abstract. Full Text Article available at: https://onlinelibrary.wiley.com/doi/pdf/10.1002/pbc.25829#accessDenialLayoutBACKGROUND: Outcomes for acute lymphoblastic leukemia (ALL) in low-income countries lag far behind high-income countries (HIC). We explored the impact of central nervous system (CNS) involvement on outcome of pediatric patients with ALL in Tanzania. PROCEDURE: Comprehensive chart review was performed to characterize CNS involvement, treatment, and outcomes of pediatric patients with ALL at Muhimbili National Hospital in Dar es Salaam, Tanzania between January 1, 2011 and December 31, 2013. RESULTS: One hundred fifty-six patients with confirmed ALL had accessible data, and 128 initiated therapy. Sixteen percent of 156 patients had a documented cerebral spinal fluid analysis by cytospin. Seventy patients (45%) had a documented lumbar puncture with intrathecal (IT) therapy within 1 week of diagnosis. Thirteen patients presented with CNS involvement at diagnosis based on cytospin and/or unequivocal symptoms. Twenty-one patients (16%) experienced CNS relapse, three of whom had CNS disease at diagnosis. Median event-free survival (EFS) for all patients was 7.9 months and estimated EFS at 24 months was 31%. For the patients with CNS involvement at diagnosis, the estimated EFS at 24 months was 45%. Only three of 21 patients with CNS relapse were still alive with a median follow up of 3 months. CONCLUSIONS: The rate of CNS disease in patients with ALL in Dar es Salaam at diagnosis and relapse was higher than that reported in HIC, and overall survival was lower. Improving outcomes will require further advances including consistent CNS prophylaxis and may include targeting high-risk patients with additional IT treatments.