We describe a case of the lethal form of osteopetrosis diagnosed prena
tally by ultrasonography. Anomalies detected on ultrasound examination
at 18 weeks' gestation included skeletal hyperdensity, communicating
hydrocephalus and short long bones. Ar 21 weeks' gestation, cordocente
sis was performed to measure the levels of calcium, phosphorus and alk
aline phosphatase. The fetus was aborted at 22 weeks' gestation. The d
iagnosis of osteopetrosis was confirmed by postmortem radiological and
histopathological analysis.