We describe our surgical technique of acute pediatric forearm lengthening and joint leveling for treatment of symptomatic forearm-length discrepancies. A retrospective clinical and radiographic analysis was performed of all patients undergoing acute forearm lengthenings of > 1.0 cm between 1983 and 1993. Twenty-four acute forearm lengthenings were reviewed with an average follow-up of 3 years. The diagnosis included osteochondromatosis in 17 patients, growth arrest in four patients, and skeletal dysplasia in three patients. Surgical indications included progressive forearm or wrist deformity, significantly limited or painful forearm rotation, or radial-head subluxation. The average lengthening was 1.5 cm (range, 1.0-2.3), which was 9% of total length (range, 3-20%). The goal for lengthening and wrist-joint leveling was near-neutral ulnar variance and was achieved in all cases. We conclude that the forearm can be lengthened acutely successfully to achieve near-neutral ulnar variance in children with forearm-length discrepancies caused by osteochondromas, growth arrests, or bone dysplasias. The surgical technique and the results are described in 24 forearm lengthenings.