Current methods for detecting ischemic placental disease are either invasive or have low sensitivity. MRI can be used to non-invasively characterize tissue hypoxia with R2* mapping. However, conventional Cartesian MRI methods are sensitive to motion artifacts due to maternal and fetal motion. In this study, a non-Cartesian free-breathing 3D stack-of-radial MRI technique (FB radial) for R2* mapping in the placenta during early gestation was investigated at 3T. In 20 subjects, placental R2* range, accuracy, repeatability, spatial variation, and temporal variation were analyzed. Results demonstrate that FB radial is an accurate and repeatable technique for R2* mapping in the entire placenta.