Non-invasive methods have replaced invasive methods in line with developments in pediatric intensive care units. (Especially methods that enable continuous monitoring) Although arterial carbon dioxide measurement is still the gold standard for the evaluation of alveolar ventilation, the need for continuous monitoring of PaCO2 and the invasive nature of this method have led to the investigation of alternative methods. To evaluate the correlation of transcutaneous CO2 (TcCO2) monitoring with PaCO2 and ETCO2 in mechanically ventilated patients in peditaric intensive care units. Single-center, prospective, observational cohort study. We enrolled 60 patients between the age of 1 month-18 years who were mechanically ventilated in pediatric intensive care unit for this singlecenter, prospective, observational cohort study from February 2019 through March 2019. Correlation analysis was performed for arterial PaCO2, end-tidal CO2, TcCO2 parameters. P<0.05 values were considered significant. The Bland-Altman plot was created for determining the agreement between the methods. The correlation of transcutaneous CO2 and end-tidal CO2 with arterial PaCO2 was evaluated, both parameters were found to be positively and highly correlated (r=0.864, p<0.001, r:0.962, p<0.001, respectively). The mean bias between the arterial carbondioxide mesaurement and transcutaneous measurement was 5.5, and limits of agreement (bias ±1.96 SD) ranged from -13.9 to 2.9. The mean bias between the arterial carbondioxide mesaurement and endtidal carbondioxide measurement was 2.3, and limits of agreement (bias ±1.96 SD) ranged from -4.1 to 8.6. In 44 measurements (88%), the TcCO2 was ±7.5 mm Hg of the PaCO2. TcCO2 seems to be a good alternative for carbon dioxide measurement, as it is non-invasive and allows continuous monitoring in view of today's intensive care conditions, but arterial PaCO2 measurement is still the gold standard method. Continuous TcCO2 monitoring provides a promising alternative to repeated blood sampling in subjects requiring mechanical ventilation for critically ill children.