Abstract: Objective：To investigate the results of prenatal diagnosis and prognosis of isolated mild ventriculomegaly fetuses. Methods：Chromosomal karyotypes were retrospectively investigated in sixty one singleton fetuses with isolated mild ventriculomegaly. The outcome of fetuses was acquired through regular follow-up. Results：In 61 cases of isolated mild ventriculomegaly， 3 （4.92%） chromosomal aberrations were detected， including 2 Down syndrome and 1 trisomy sex chromosome. In 50 cases which the IgM of toxoplasma， cytomegalovirus and rubella virus was detected， one case was positive with rubella virus IgM. Follow-up was successful in 55 cases， 8 were terminated because of various causes， including 3 chromosomal aberrations and 1 rubella IgM positive case. In 47 alive cases， 1 was found to have multi-maformation after birth， 1 died in neonatal period，2 with developmental retardation， 43 cases （91.49%） with normal development. Conclusions：Prenatal diagnosis is necessary for the fetuses with isolated mild ventriculomegaly. Apart from chromosome aberration and congenital infection， most of isolated mild ventriculomegaly fetuses have good prognosis.

Key words: Ultrasonography, prenatal, Fetus, Lateral ventricles, Prenatal diagnosis, Chromosome aberrations