BACKGROUND CONTEXT Adolescent idiopathic thoracolumbar scoliosis (Lenke 5) can be operatively managed with anterior or posterior approaches. Each approach has unique surgical advantages and limitations. PURPOSE To compare direct costs associated with anterior and posterior operations for thoracolumbar scoliosis in children. STUDY DESIGN/SETTING Single-center retrospective cohort. PATIENT SAMPLE Adolescents who underwent anterior or posterior operations for thoracolumbar AIS (Lenke 5). OUTCOME MEASURES Total and direct costs. METHODS Consecutive review of adolescents (age>10 years) who underwent anterior or posterior operations for thoracolumbar scoliosis (Lenke 5) at a single institution by a single surgeon. Inclusion criteria included idiopathic scoliosis, curve magnitude >450, and non-structural thoracic scoliosis. Direct costs of the index hospitalization were identified from medical billing data. Not included in direct cost data were charges and surgeon fees. Costs data were stratified and compared based on the surgical approach using non-paired Student T-tests; p RESULTS A total of 17 children (average age 15.3±1.9 years, girls-13, average curve magnitude 51.10±6.20) were analyzed. Ages and curve magnitudes were statistically similar between anterior (n=10; boys 2, girls 8) and posterior (n=7; girls 5) operations. Anterior operations had significantly fewer levels fused (5±0 vs 6±0.9), significantly longer OR times (449±40 v. 308±26 mins), and more patients admitted to ICU post-op (30% vs 14%). While hospital lengths of stay (LOS) (5±2.1 v. 4±0.5 days) were not different, 2 anterior patients had LOS>7 days due to difficult pain control and C. diff colitis. Anterior operations were associated with significantly greater direct costs ($40,161±$3,668 v. $34,469±$7,846). However, when the 2 anterior patients with extended LOS were excluded, direct costs were not statistically different (anterior: $39,990±$3,855 v. posterior: $34,469±$7,846). In addition to room/board and ICU care, supplies/instrumentation, and operating room services were major drivers of cost irrespective of approach. CONCLUSIONS For thoracolumbar AIS treated by anterior or posterior approaches, major drivers of cost were supplies/instrumentation, OR services, room/board, and ICU. Anterior operations had significantly greater direct costs due to more ICU admissions postoperative and more episodes of prolonged LOS. Minimizing LOS, ICU admissions, and postoperative complications are important to contain costs. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.