Pediatric arterial ischemic stroke (AIS) is increasingly diagnosed and carries significant risks of recurrence, morbidity, and mortality. Anticoagulant therapy (ACT) is commonly prescribed in childhood AIS. Hemorrhagic complication rates in pediatric stroke are unknown, and adult safety data are of limited applicability. We analyzed a prospectively enrolled cohort of children (aged 1 month-18 years) with acute AIS selected using standardized criteria for protocol-based ACT over14-year period. We assessed ACT-associated intracranial hemorrhage (ICH), including frequency, clinical and radiologic characteristics, predictors, and outcome. Among 215 children with AIS, 123 received ACT within 7 days after diagnosis. During anticoagulation, 14 (11%) children developed new or increased ICH, all within 26 days from diagnosis. ICH was symptomatic in 5 (4%), asymptomatic in 9 (7%), and mild (European Cooperative Acute Stroke Study grades HI1 or HI2) in all but 1 child (ECASS PH-2). Long-term neurologic outcomes after ACT-associated ICH in survivors were abnormal in 73% (8/11). Comparably, 12 of 75 (16%) children treated without anticoagulation developed new or increased ICH on follow-up imaging (P = .3507). We conclude that ACT is relatively safe in children with AIS, with a 4% risk of symptomatic ICH. Based on the safety of ACT in our study, clinical trials of ACT in childhood AIS are warranted.