Amniocentesis, introduced 40 years ago, has become a commonly performed obstetric procedure. Its applications, originally related to Rh isoimmunization, have been expanded to include assessment of fetal maturity and prenatal genetics. The maternal complications of this procedure have been stressed for some time, but with increasing frequency fetal complications are being observed. This report reviews the maternal and fetal complications of amniocentesis and illustrates the potential fetal morbidity with a case report of a tension pneumothorax in a neonate resulting from fetal puncture during diagnostic amniocentesis.