47 children (16 years or younger) who sustained a diaphyseal both-bone forearm fracture without need for reduction were randomized to evaluate the safety of early conversion to below-elbow cast (BEC) during regular above-elbow cast (AEC) treatment. Patients were administered casts for 6 weeks but those in the BEC group were administered a BEC after 3 weeks with an AEC. Patients were evaluated for limitation of pronation and supination over 6 months, along with several secondary outcomes. The evidence presented in this study demonstrated that early conversion BEC from AEC did not result in more re-displacement of the fracture compared to 6 weeks of AEC only. No significant differences were revealed between groups based on clinical and radiographic outcomes.