The study evaluated the accuracy of MRI in the diagnosis of 22 angular pregnancy cases and 37 interstitial pregnancy cases retrospectively during the first trimester. Two senior obstetrics radiologists reviewed the MR images and analyzed several features. The study found two key features were useful to diagnose angular pregnancy, namely, “medial free edge” and “medial free edge plus above-cutoff endometrial thickness”. One key feature to diagnose interstitial pregnancy was “intact lateral junctional zone”. MRI is a novel imaging approach to make the precise differential diagnosis of angular pregnancy and interstitial pregnancy.