In patients with tetralogy of Fallot (ToF) or ToF-like anatomy, factors possibly impacting the longevity of biological valves in pulmonary position were investigated. Between 1997 and 2017, 79 consecutive hospital survivors with a median age of 8.7 years (range 0.2-56.1 years; IQR 14.8 years) with ToF or ToF-like anatomy underwent surgical implantation of Contegra™ (n=34), Hancock™ (n=23), Perimount™ (n=9), pulmonary homograft (n=9), and miscellaneous (n=4) conduits. The median internal graft diameter was 19mm (range 11-29mm; IQR 8mm) which refers to a median z-score of 0.6SD (range -1.8-4.0SD; IQR 2.1SD). The median time of follow-up was 9.4 years (range 1.1-18.8 years; IQR 6.0 years). Thirty-nine patients (49%) underwent surgical (n=32) or interventional (n=7) pulmonary valve re-replacement. Univariate cox regression revealed patient age (p=0.018), body surface area (p=0.004), internal valve diameter (p=0.005) and prosthesis z-score (p=0.018) to impact valve longevity. Multivariate cox regression analysis, however, did not show any significant effect (likely related to multicollinearity). Subgroup analysis showed that valve revised patients have a higher average z-score (p=0.003) and a younger average age (p=0.007). A decreased longevity of biological valves in pulmonary position is related to younger age, lower valve diameter, and higher z-score. Because valve size (diameter and z-score) can be predicted by age, patient age is the crucial parameter influencing graft longevity.