During the summer of 2007 in a private garden in Smržice (district Prostějov, Czech Republic) symptoms of powdery mildew on Caragana arborescens were recorded. Until now at least two powdery mildew species (Microsphaera trifolii var. trifolii and M. palczewskii), both differing in some basic morphological features, have been recorded for the genus Caragana. Comparison of our measurements with previous descriptions of powdery mildew samples found in the Czech Republic on Caragana arborescens identified our species as Microsphaera palczewskii (newly Erysiphe palczewskii). This is probably the first detailed record of this species on C. arborescens in the Czech Republic. Fungus from Czech Republic was compared with the material collected in 2007 in Vienna (Austria). The aim of this paper was to provide a detailed comparative morphological characterisation of E. palczewskii anamorph and teleomorph found in the Czech Republic and in Austria. Serious reduction of the anamorph, caused by hyperparasitic fungus Ampelomyces quisqualis, was recorded on the sample from Austria.