Objective: To determine whether the size of an intravenous catheter influences the cannulation success rate and procedure duration among military medics. Methods: According to a prospective, randomized, controlled crossover study design, 114 military medic cadets were paired and inserted 14-gauge (14G) and 16G intravenous catheters into veins in the antecubital fossa. Success rate and procedure duration were determined. Results: The overall success rate for 14G and 16G catheters was 80 and 86%, respectively. Average procedure duration was 33 ± 14.7 and 35.2 ± 14.9 seconds, respectively. No significant differences were found in either success rate or procedure duration between the examined catheter sizes. Conclusion: Successful intravenous cannulation was unaffected by catheter size. Therefore, 14G intravenous catheters are recommended for use by military medics on the battlefield.