Paul Oskar Morawitz (April 3, 1879 in St. Petersburg – July 1, 1936) was a German internist and physiologist whose most important work was in studying the coagulation of blood.

In 1907 he completed a dissertation on blood circulation (for his Habilitation), and he was appointed in the same year as chief clinician of the University clinic at Freiburg im Breisgau.

He progressed to become the Ordinarius and Director of the Medical inpatients at Greifswald in 1913, and in 1921 he took up a position in Würzburg.

[1] Morawitz was a pioneer in the study of coagulation, and a 1905 landmark paper[2] is still regarded as a springboard for further study of the physiology of blood; he perfected observations made earlier by Alexander Schmidt and described four coagulation factors: fibrinogen (I), prothrombin (II), thrombokinase (III) and calcium (IV).

[1] He is commemorated by the annual "Paul Morawitz prize" by the Deutsche Gesellschaft für Kardiologie (German Cardiological Association).