Diagnostic tests are a cornerstone in modern medicine. They are used not only to confirm the presence of a disease but also to rule out the disease in healthy subjects. Tests with two outcome categories (i.e. presence/absence) are known as dichotomous tests. Their inherent validity is determined by sensitivity and specificity and the receiver operating characteristic (ROC) curve is known to be a simple, yet complete plot that displays the full picture of trade-off between the sensitivity (true positive rate) and (1- specificity) (false positive rate) across a series of cut-off points. Our study found that, even in the early hours of paroxysmal atrial fibrillation, there were significant changes in major indicators of fibrinolysis, namely plasminogen level, t-PA level, PAI-1 activity, α2-antiplasmin activity, vitronectin and D-dimer plasma levels. We believe that they are closely related and stem from the disease itself. This gave us reason, using these indicators as predictors, to search for a diagnostic option to rule out PAF. We used statistical models of logistic regression analysis and ROC to achieve this. Values of p