Leptophlebiidae, a diverse family of Ephemeroptera with a worldwide distribution, plays an important role in freshwater ecosystems. However, Leptophlebiids are only sparsely represented in the fossil record of midCretaceous Kachin amber, limiting our understanding of its evolutionary history. Here, we describe a new species of Leptophlebiidae, Crephlebia kachinense sp. nov., based on a male imago preserved in mid-Cretaceous Kachin amber from northern Myanmar, thereby contributing to knowledge of the diversity of this extinct genus. The new species differs from Crephlebia zhoui Chen & Zheng, 2024 in its wing venation, characterized by the absence of free intercalary veins and more crossveins, as well as in the morphology of the penis. This discovery reveals a higher palaeodiversity of Leptophlebiidae during the Cretaceous period, particularly in the fossil resins of Myanmar. urn:lsid:zoobank.org:pub:29F182B6-768B-42B9-AE82-D33DB7A830F6.