In Scandinavia the leaves of cloudberry ( Rubus chamaemorus L.) commonly show leaf spots. Fungus fructifications are never seen on the spots during the summer. On leaves overwintered under snow near Tromso (Norway), perithecia of a Mycossphaerella species appeared on the old spots in spring. This fungus is described under the name Mycosphaerella Joerstadii v. Arx spec. nov. On some leaves, another fungus is found, which was proved to be identical with Sphaerella chamaemori Karst, and which has to be named Venturia chamaemori (Karst.) v. Arx comb. nov.