Six cases of unilateral pulmonary agenesis with skeletal and other deformities have been diagnosed in our hospitals. The various pulmonary, spinal, rib and limb anomalies with their possible inter-relationships were examined and described in detail and comparison with previously reported cases was made. It became apparent that the limb abnormalities which most constantly involved hypoplasia of the phalanges of a thumb with varying metacarpal and radial anomalies, were ipsilateral to the pulmonary agenesis in all cases. The spinal deformities involved degrees of failure of segementation of T1-T3 with other vertebrae randomly involved. Rib abnormalities also varied and did not necessarily correspond to the same side as the pulmonary agenesis. The concept of the anomalies all being part of a group of neural crest injuries was then explored.