To assess the efficacy and safety of diagnostic cordocentesis.Between January 1991 and May 2004, 2,010 cordocentesis were performed in the outpatient setting in 2,010 women with singleton pregnancies. A fixed needle guide and a 22-gauge percutaneous needle were used and no more than 2 attempts were allowed at 1 visit. In most cases, the umbilical vein was the target vessel. The results of each procedure and pregnancy outcomes were recorded and analyzed.The most frequent indication for cordocentesis was risk of severe thalassemia (59.0%), followed by a need for rapid karyotyping (30.0%). Most of the procedures (97%) were performed in the free cord loop and the remaining at the cord insertion. The overall success rate was 98.4%, with 80.0% of the successful procedures performed at the first needle insertion and the remaining 20% at the second insertion. Transient bleeding was observed at the puncture site in 19.8% of cases and transient fetal bradycardia in 4.9% of cases. The total fetal loss and cordocentesis-related loss rates within 2 weeks of cordocentesis were 2.7% and 1.0%, respectively, before 24 weeks of gestation and 1.9% and 0.8% after 24 weeks. The other obstetric complications were unremarkable.Cordocentesis is a simple, safe, and reliable procedure for prenatal diagnosis.