BACKGROUND Reconstructions of forearm fracture nonunions are frequently complex. A few studies that help guide the treatment of forearm nonunion have been reported. We offer a novel surgical technique to treat nonunion of the forearm using a regional vascularized bone graft. METHODS Four females and 5 males ranging from 27 to 74 years of age with 7 ulna and 2 radius nonunions were surgically treated by pedicle grafting with a posterior interosseous bone flap (PIBF) and internal fixation with a plate. There were no cases with extensive soft tissue damage or infection. Pre- and postoperatively (mean 21 months), all patients were assessed by radiographs and for function by the Disabilities of the Arm, Shoulder and Hand (DASH) score. RESULTS Function of the upper extremity was improved in all patients. DASH scores improved from 61.2 points pre-operatively to 12 points at final follow-up. All nonunions were united uneventfully. CONCLUSIONS Following debridement of the necrotic tissue, the bone defect can be filled with a vascularized graft from posterior interosseous pedicles. Pedicled PIBF is a safe and useful novel technique in cases of atrophic or hypertrophic nonunion of the middle third of the radius or proximal two-thirds of the ulna.