One hundred sixty-seven plasma samples of free-living birds of prey from Berlin and Brandenburg State (Germany) were tested for antibodies against avian adenovirus (FAV, group I) using agar gel precipitation test. Antibodies to FAV were detected in seven (4%) of 167 total samples. The positive samples originated only from common buzzards (Buteo buteo; seven [12%] of 59). This serologic survey provides evidence of natural exposure of free-living common buzzards from eastern Germany to adenoviruses.