Purpose: Pediatric trigger thumb is a condition of flexion deformity of the interphalangeal (IP) joint. The known surgical treatment is the release of the flexor pollicis longus by transection of the A1 pulley. We report two cases of pediatric trigger thumb that were resolved by releasing of additional pulley as well as A1 pulley. Methods: From March 2006 to April 2008, a total of 10 children with trigger thumb were operated. In two cases, transection of only the A1 pulley was insufficient to relieve the triggering. When more distally dissection, we found an additional pulley. After release of the additional pulley, the full extension of IP joint is obtained. Results: There were no significant complications. In 8 cases, the trigger thumbs were resolved by transecting only the A1 pulley, does not extend beyond the base of the proximal phalanx. In one case, the additional pulley was found to be more distal to the A1 pulley. It was necessary to extend the release up to the half in the proximal phalangeal shaft. In other case, the additional pulley was immediately adjacent to the A1 pulley. Conclusion: In most cases of trigger thumb, division of just A1 pulley is sufficient to relieve the triggering. However, dividing the A1 pulley in two patients proved to be insufficient to relieve the flexed deformity. In these cases, we found that the additional pulley, different from previous known A1 pulley, had existed, which must be transected to allow full excursion of flexor pollicis longus.