Purpose: Plasminogen activator inhibitor-1 (PAI-1) participates in thrombotic, fibrinolytic, inflammatory and metabolic cascades. Since previous studies have focused on tissue and blood level concentrations, our goal was to investigate for the first time the independent relationship between plasma PAI-1 activity in resectable non small cell lung cancer (NSCLC) taking into consideration its several interfaces and study its diagnostic and prognostic potential., Methods: In an adequately powered case-control study, plasma PAI-1 activity, metabolic parameters, classic adipokines, hemostatic, inflammatory and tumor biomarkers were measured in 110 consecutive patients with resectable NSCLC and 110 healthy subjects matched on age, sex and date of blood draw., Results: NSCLC patients exhibited significantly higher PAI-1 activity compared to controls (p<0.001). In NSCLC cases, PAI-1 activity correlated with somatometric variables, insulin, WBC, antithrombin III, protein C, plasminogen, IL-6 and tumor size (p<0.05). Plasma PAI-1 activity was independently associated with NSCLC beyond risk factors associated with NSCLC (OR:6.9, 95%CI:2.9-16.6, p<0.001). Plasminogen activity and body mass index emerged as independent predictors of PAI-1 activity in cases. Due to its high specificity, PAI-1 activity could represent a potentially useful parameter in ruling out NSCLC, alone or in combination with serum tumor markers associated with NSCLC., Conclusions: PAI-1 activity, reflecting PAI-1 functionality, may represent a potentially useful biomarker in NSCLC associated with thrombotic, tumor-promoting and metabolic networks. More clinical studies are needed to explore whether PAI-1 activity may be a practical biomarker in the risk assessment of NSCLC, at the crossroads of hemostasis and metabolism.