By isoelectric focusing in a pH range of pH 3.5 – 9.5 or of pH 5–8, and by using a functional or an immunological detection, a genetic polymorphism of plasminogen can be demonstrated. In Caucasoids, 2 common alleles – PLG*A (frequency 0.67) and PLG*B (frequency 0.30) – as well as several rare variants (sum of their frequencies 0.03) exist. Systematic studies on the functional activity of the various plasminogen gene products should be performed in order to analyse whether or not a difference of plasminogen activity can be observed amongst the possible phenotypes and in order to see whether or not the various plasminogen phenotypes have any clinical significance.