Study Design: A retrospective comparison of pediatric patients weighing less than 30 kg who underwent thoracoscopic anterior spinal release and fusion for deformity correction. This group was compared to two control groups: patients weighing over 30 kg (thoracoscopic) and patients under 30 kg (open)., Objective: To determine the efficacy and safety of thoracoscopic anterior spinal release and fusion in small pediatric patients weighing less than 30 kg., Summary of Background Data: Recently, thoracoscopic methods have been utilized to perform anterior spinal release/fusion in the treatment of pediatric and adult spinal deformity. The safety, efficacy, and technical challenges of thoracoscopic spinal surgery in small children have not been established., Methods: "Small thoracoscopic children," defined as those under 30 kg who had thoracoscopic spinal surgery, are the main focus of this study. They were compared to "large thoracoscopic children" (>30 kg, thoracoscopic surgery) and "small open children" (<30 kg, open surgery). Preoperative, intraoperative, and postoperative parameters were analyzed., Results: Small thoracoscopic children (n = 33) had greater estimated blood loss/kg body weight (13.6 mL/kg vs. 6.2 mL/kg; P= 0.003), greater chest tube output (27.5 mL/kg vs. 17.1 mL/kg; P= 0.003), and a longer intensive care unit stay (4.2 days vs. 1.5 days; P= 0.001) than did large thoracoscopic children (n = 48). Conversion to an open thoracotomy occurred in one patient from each of the thoracoscopic groups. Small thoracoscopic children required more anesthesia preparation time (79.2 minutes vs. 64.2 minutes; P= 0.002) than the small open children (n = 25). There was no significant difference in estimated blood loss, chest tube output, or intensive care unit stay between these two groups. Additionally, no significant difference was found between the three groups with regard to the number of discs excised, operative time, and total hospital stay., Conclusion: Despite the decreased working space within the chest and difficulties of selective intubation, anterior thoracoscopic surgery for spinal release and fusion can be performed as safely in "small" children as in "large" children; however, additional intraoperative challenges should be anticipated. Although the outcomes were similar in the small thoracoscopic children compared to the small open children, the authors believe that very small patients (under 20 kg) should remain a relative contraindication to thoracoscopic surgery, especially during a surgeon's learning curve.