A global survey of the spread of the Platanus powdery mildew, Erysiphe platani, has been carried out. E. platani teleomorph formation was recorded in countries where the fungus anamorph has been present for several years. The first findings of chasmothecia were recorded in Austria, Czech Republic, France, Italy and Slovakia. New records of E. platani (including the teleomorph) were found in Belgium, Croatia and Denmark. The occurrence of this fungus in Sweden and in two countries of North Africa (Algeria and Morocco) was confirmed. Descriptions of morphological features, illustrations, and worldwide distribution of E. platani are provided. Herbarium collections of powdery mildews on Platanus spp. were re-examined and revised. The occurrence of Phyllactinia guttata on Platanus is discussed and questioned.