In those forms of chronic pulmonary disease in which the course is atypical, the symptoms severe and persistent, the physical examination inconclusive and the laboratory reports negative, the study of fresh, unstained preparations of the sputum and, at necropsy, of lesions macerated in a strong solution of potassium hydroxid often reveals unexpected and suggestive findings. By this method of study we found, in the sputum of one case and in the pulmonary lesions of three cases, an unusual organism that has not been described in association with disease in man or in animals. This organism is characterized by its pyriform or club shape, its beaded or septated structure, and its diffuse brown pigmentation. Occasionally, it is associated with a small, rounded, nonpigmented body with a roughened surface covered with flattened spurs giving it the appearance of a golf ball. The beaded, pyriform body is similar to the septated spore of