The occurence and morphological appearance of ectopic pulmona ry cartilage and bone in chickens was studid. Its incidence was shown to vary in different breeds of chickens. These Cartilage and bone was observed in 3 week old chicks up to 15 weeks old. The previous theories of the ectopic pulmonary cartilage genesis were discussed. It was concluded that they do not originate from disease process, but are probably abnormal embryonic induction of mesenchymal or cartilaginous germ cells displaced from bronchi.