Purpose The purpose of this study was to determine the risk factors for loss of reduction in patients with an isolated distal radius fracture and intact ulna. Methods Outpatient records and initial, post-reduction, and follow-up radiographs of children with displaced distal radial metaphyseal fractures and intact ulnas that required closed reduction and casting at our institution were reviewed for demographic factors, body mass index (BMI), initial fracture displacement, residual displacement after reduction, and 3-point cast index. Loss of reduction was defined as angulation C15°in the coronal plane for all ages and/or angulation C20°in the sagittal plane for patients C11 years of age and C30°for children \11 years of age. Additionally, all patients who were remanipulated and/or pinned were considered to have lost reduction. Results Thirty-five of the 76 patients in our series met the criteria for loss of reduction (46%). Multivariate logistic regression revealed that initial angulation in the coronal plane and post-reduction translation in the coronal plane were independent predictors for loss of reduction. Patients with [11°of initial angulation in the coronal plane were 6.3 times as likely to lose reduction (confidence interval [CI]: 1.43-28.3, P = 0.015) and those with any amount of residual translation in the coronal plane after closed reduction were 7.8 times as likely to lose reduction (CI: 2.5-24.0, P \ 0.001). Conclusion Our study, the largest dedicated series of distal radial metaphyseal fractures with intact ulnas, indicates that loss of reduction is common, and that risk factors include initial angulation in the coronal plane and postreduction translation in the coronal plane.