The case of thanatophoric dysplasia of the fetus was described. The disease was recognized by ultrasound. Karyotyping was successful after fetal blood sampling under continuous ultrasound guidance. An inversion of chromosome 10 was detected in the affected fetus. The confirmation of the thanatophoric dysplasia was done after termination of the pregnancy. The same inversion was detected in unaffected mother. Prenatal diagnosis was made in the next pregnancy. The result was an unaffected newborn delivered on term.