Background The traditional treatment of traumatic hemothorax (HTX) is large bore chest tubes (CT) ≥28Fr. Recent evidence shows 14Fr pigtail catheters are as effective in drainage of HTX as larger CT. However, this has not been shown in 14Fr Thal tubes, a straight chest tube placed utilizing Seldinger technique. Methods A single center, prospective randomized controlled trial was performed at an ACS verified Level 1 trauma center comparing 14Fr Thal CT (14CT) to 28Fr CT (28CT) between May 2017 and September 2021. The primary outcome was failure of drainage of hemothorax requiring additional intervention. Secondary outcomes included duration of chest tube placement, length of stay, tube-specific complications, and 90-day hospital readmission. Farrington-Manning approach was used for non-inferiority tests. Wilcoxon 2-samples test or t test was used for continuous variables, and Pearson chi-square or Fisher exact test was used for categorical variables. Results 109 patients were included in the randomized trial. There were 54 patients in the 14CT cohort, and 55 patients in the 28CT cohort. The primary outcome of drainage failure was similar between groups (8.3% 14CT vs 3.9% 28CT). Using a 15% non-inferiority margin 14CT is non-inferior to 28CT. No differences were identified in secondary outcomes. Conclusion 14Fr Thal tubes have similar efficacy in drainage of traumatic hemothorax when compared with 28Fr chest tubes with similar complication rates (NCT03167723).