Background: Umbilical vein cutdown in neonates as an important method of accessing vascular is very important in cases in which peripheral vein is not available and it is not possible to cut down another vein. The umbilical vein is believed to become thrombotic and lumen is closed and unusable one week postpartum. Methods: In this cross-sectional study, all neonates who were admitted to the surgical ward of Mohammad Kermanshahi Hospital in Kermanshah, who needed emergency vein access and who were unable to have vein cutdown elsewhere during 2012-2014 were enrolled. The participants were divided to four age groups (one week to four weeks) and the possibility of umbilical vein cutdown was assessed in each group. Results: Of all participants, 25 infants were girls and 20 were boys. The umbilical vein cutdown was successful in 39 patients (86.7%), and failed in 6 patients (13.3%). The procedure was successful in all infants younger than 3 weeks old except for one case, while the success rate rapidly decreased after 3 weeks old. Conclusions: Umbilical vein cutdown was successful in infants under three weeks old and it was not possible afterward due to umbilical vein thrombosis. One-week age restriction for umbilical vein cutdown is questionable and requires further randomized trials with a control group to reach definitive conclusions.