Although the use of ultrasound for the insertion of central catheters has proven to be cost-effective in adults, it is not known if this is the case in the neonatal population. This study compared the cost-effectiveness of ultrasound-guided umbilical venous catheterisation with conventional catheterisation in a neonatal intensive care unit of a Public University Hospital. A retrospective observational study was conducted on newborns that required an umbilical venous catheter before completing their first 24hours of extra-uterine life. Two retrospective cohorts were formed, including one with ultrasound-guided catheterisation and the other with conventional catheterisation. The effectiveness was measured using 2 variables: placement of ideal position and insertion without complications. The cost of human and material resources (consumable and non-consumable), the cost-effectiveness ratio, and the incremental cost-effectiveness ratio were estimated, as well as carrying out a sensitivity analysis. Catheter obstruction was more frequent in guided catheterisation than in conventional catheterisation (7.7% vs. 0%, p=.04) and catheter dysfunction was higher in the latter (79% vs. 3.8%, p