The Wilson-Mikity Syndrome is a newly described respiratory ailment of very premature infants. It is typified by its characteristic clinical course, with onset after a period of well-being, and radiologic findings of coarse infiltrates alternating with cystic changes. At least four cases have occurred in the last two years at the University of California Medical Center, San Francisco. An exemplary case is given. The pathophysiology of the syndrome appears to relate primarily to abnormal ventilation perfusion relationships resulting from uneven lung compliance. It is suggested that the syndrome results from a distortion of the normal development of the fetal lung.