Background: Incorrectly positioned gastric tubes occur in approximately 60% of infants hospitalized in the neonatal intensive care unit (NICU), increasing the risk of potentially serious complications. Purpose: To compare 3 methods of determining gastric tube insertion length in infants in the NICU. Methods: In this randomized triple-blind clinical trial, 179 infants admitted to the NICU were randomized to have their gastric tube insertion length determined by 1 of 3 methods: (1) the nose, earlobe, mid-umbilicus (NEMU) method, (2) a weight-based method, or (3) an age-related height-based (ARHB) method. Positioning of the gastric tube was verified by radiograph. R software was used for analyses. To compare categorical variables, Fisher's exact test, χ2 tests, and simulated χ2 tests were used. Results: Overall, infants had a mean gestational age of 35 weeks, 115 (58.8%) were male, and the mean birth weight was 2481.5 g. Upon radiological assessment, 145 gastric tubes (81.3%) were correctly positioned in the gastric body or greater curvature of the stomach with the weight-based method having the highest percentage of correctly positioned gastric tubes (n = 53; 36.6%), followed by the ARHB method (n = 47; 32.4%) and the NEMU method (n = 45; 31.0%). No significant differences were identified between groups (P = .128). Implication for Practice and Research: Despite the NEMU method being the most commonly used method in clinical practice, the weight-based and ARHB methods to determine gastric tube insertion length may be more accurate.