In the past two decades, European ash trees (Fraxinus spp.) have been severely damaged by ash dieback disease of which causal agent is a fungal species called Hymenoscyphus fraxineus (anamorphic stage Chalara fraxinea). Recent molecular phylogenetic and population genetic studies suggested that this fungus may have been introduced from Eastern Asia to Europe. In the course of fungal biodiversity survey in Korea, H. fraxineus-like apothecia were collected from fallen leaves, rachis and petioles of Korean ash and Manchurian ash trees. The morphological and ecological traits of these materials are provided, supplemented by ITS rDNA sequence comparison of H. fraxineus strains collected from Europe, China and Japan.