Following a request from the European Commission, the EFSA Panel on Plant Health (PLH) performed a pest categorisation of Mycodiella laricis-leptolepidis, a well-defined and distinguishable fungal species of the family Mycosphaerellaceae. The former species name Mycosphaerella laricis-leptolepis is used in the Council Directive 2000/29/EC. The pathogen is regulated in Annex IAI as a harmful organism whose introduction into the EU is banned. M. laricis-leptolepidis is native to East Asia and causes a disease known as needle cast of Japanese larch (Larix kaempferi = Larix leptolepis) and Kurile larch (Larix gmelinii). European larch (Larix decidua) was found to be susceptible to the disease as introduced tree in Japan. The fungus could enter the EU via plants for planting and cut branches of Larix spp. It could establish in the EU, as hosts are present and climatic conditions are favourable. The pathogen would be able to spread following establishment by human movement of infected plants for planting and by dissemination of ascospores. Should the pathogen be introduced in the EU, impacts can be expected due to needle loss in larch forests and plantations, thus leading to reduced tree growth and ecosystem service provision. The use of resistant/tolerant varieties can reduce the impacts. The key uncertainties are the knowledge gaps concerning (i) the potential range of spread through ascospores and (ii) the level of impacts in the native range of the pathogen. The criteria assessed by the Panel for consideration as a potential quarantine pest are met. For regulated non-quarantine pests, the criterion on the pest presence in the EU is not met.