Objectives: To examine the effect of drug level-based personalized treatment of adalimumab in children with Crohn's disease. Design: A prospective, randomized, open label study. Setting: Pediatric gastroenterology centers. Participants: Children 6 year to 17 years who are diagnosed with CD and are planned to receive adalimumab treatment. Main outcome measures: Pediatric Crohn's Activity Index (PCDAI) at 48 and 72 weeks. Secondary outcome measures: Corticosteroids free remission rates and on adalimumab at 48 and 72 weeks. The effect of routine adalimumab drug monitoring-based treatment on trough levels and anti-adalimumab antibodies during therapy.