The infection of our indigenous wild birds by the parasite Collyriclum faba represents a rare event. The adult trematodes reside in the subcutaneous tissue of the host, where prominent cysts can be found. In summer 1988, two cases were diagnosed, in a house sparrow (Passer domesticus) and in a goldcrest (Regulus regulus), which led us to a description of this unusual parasitic disease, whose cycle still remains unknown, and to a review of the prior known appearances in Switzerland. In the time between 1960 and 1989, a total of 2070 wild birds were examined in our Institute. In only four cases could an infection with C. faba be demonstrated. All of the affected birds belonged to the order of the Passeriformes. The occurrence rate of infestation among all wild birds was of 0.2%, and of 0.6% within the order of the Passeriformes. On the basis of this infection rate in our samples, we conclude that the rate of C. faba infections in wild birds of Switzerland is extremely low.