Surgical repair of Truncus arteriosus aims to improve long term survival. A clear understanding of the natural history and achievable surgical outcomes informs surgical decision making with respect to the timing of surgery. We sought to determine if it is ever too late to repair T. arteriosus. Pubmed and Google scholar were searched between January 1st 1966 and July 31st 2021. The proximal similarly model was used to determine the most externally valid natural history and surgical outcome data. The most externally valid data were used to develop a composite survival graph to help clinicians optimize surgical decision making. Four hundred and twenty eight results were retrieved. Five studies representing 938 patients who had repair of T. arteriosus were included for external validity assessment. The resultant composite graph suggests that repair after 5 month of age, may not improve 15 year survival when compared to non-operative care. T. arteriosus repair after 5 months of age may not improve survival. Key words: Pediatric, truncus artriosus, operative, outcomes.