Objective: This review aims to make a brief overview of blood biomarkers’ clinical decision limits, possibly aiding in outcome prediction in all-aged Tetralogy of Fallot patients. Potentially, these biomarkers could also assist in necessity and timing of pulmonary valve replacement. Methods: Studies with all-aged patients with Tetralogy or Pentalogy of Fallot and blood biomarkers, BNP, NT-proBNP and hs-cTn, usage in clinical outcome prediction were included. Additionally, pulmonary valve replacement indications were considered. Other congenital heart diseases, biomarkers irrelevant to clinical outcome and associated pathologies or physiological status were the exclusion criteria. Keywords, Tetralogy and Pentalogy of Fallot, pulmonary valve replacement, blood biomarkers, yielded 69 suitable studies from Google Scholar, PubMed and Web-of-Science. 30 studies were selected. Results: Blood biomarkers were increased in TOF patients in comparison to controls; the higher the values, the worse adverse outcomes. Blood biomarkers combined with other biomarkers, imagistic methods or parameters showed promising results in outcome prediction. Conclusions: Blood biomarkers are validated as follow-up predictors in congenital heart disease paediatric patients. Further research is required to establish age-appropriate clinical decision limits. Pulmonary valve replacement timing remains controversial.