A retrospective survey was made to study the prenatal diagnosis on neural tube defects(NTD) by ultrasound examination from 1990 to 1993 in China. A total of 2158 livebirths and stillbirths affected by NTD with 28 weeks or more of gestation were investigated in 233 hospitals of 28 provinces, municipalities and autonomous regions all over the country. The results showed that 61.8% of the NTD were diagnosed prenatally, and 56.5% of the NTD were diagnosed by ultrasound examination. The ratios of anencephaly, myelocele and meningocele diagnosed prenatally by ultrasound examination were 66.7%, 62.5% and 52.5% respectively. Thoracic(46.4%) and lumbar (43.4%) spina bifida were diagnosed more frequently than cervical(35.5%) and sacral(31.7%) spina bifida. The ratios of prenatal diagnosis on NTD by ultrasound examination in provincial, municipal, county, and factory hospital units were 55.7%, 59.4%, 49.0% and 57.2% respectively. The ratios of prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993 were 53.5%, 55.8%, 60.7% and 54.7% respectively. There was an increase in the prenatal diagnosis of NTD by ultrasound examination from 1990 to 1993. The ratios of prenatal diagnosis of NTD in county hospitals by ultrasound examination were relatively low. Anencephaly, myelocele and meningocele were more frequently diagnosed by prenatal ultrasound examination.