<h3>Purpose</h3> The detection of cell-free DNA (cfDNA) in EVLP perfusate has been shown to be a good indicator of apoptosis and potentially reflects lung injury. Biomarker scoring algorithms have been developed that predict donor lung injury and outcomes following ex vivo lung perfusion (EVLP); however, the mechanisms behind what is driving the poor algorithm scores remains unknown. In this study, we investigated the relationship between cfDNA in EVLP perfusate and donor lung suitability as predicted by biomarker algorithms. <h3>Methods</h3> A total of n=42 clinical EVLP cases were used in this single-center, retrospective cohort study; n=23 were EVLP cases that were transplanted and n=19 were EVLP cases deemed unsuitable for transplantation. Perfusate samples were collected after 1h and 4hr of perfusion. Perfusate supernatants following centrifugation were collected, snap frozen, and stored at -80C prior to cfDNA testing. cfDNA was extracted and quantified using Agilent Bioanalyzer. Results from a biomarker scoring algorithm were obtained and used for comparison with cfDNA data. <h3>Results</h3> The probability that a donor lung will be declined after EVLP correlated with cfDNA levels measured at 4h as well as the change in cfDNA levels between 1 and 4h (Figure 1A; 4h p<0.0001, r=0.59; delta p<0.001, p=0.56). Conversely, a negative correlation was observed between the amount of cfDNA and the probability that a recipient would be extubated in less than 72h post-transplant (Figure 1B; 4h p<0.001, r=-0.56; delta p<0.001, r=-0.54). A cfDNA cut-off of 463ng/mL after 4h of perfusion or an increase of 345ng/mL of cfDNA between 1 and 4h of perfusion were significant prognostic indicators of donor lung decline or extubation >72h post-transplant (Figure 1C and 1D). <h3>Conclusion</h3> The amount of cfDNA in EVLP perfusate correlates with the prognosis of lungs on EVLP using biomarker algorithms. This study indicates that apoptotic cell death may be an explanatory feature for algorithms that predict lung injury and outcomes following EVLP and transplantation.