This paper, which presents first results of a wider book project, will reconstruct the influence of the so-called ‘radical wing’ of the Reformation, above all Anabaptism, Socinianism, and Antitrinitarism, on the tradition of natural philosophy that had established itself in particular in Veneto through the works of Pietro Pomponazzi, Agostino Nifo, and Giacomo Zabarella. Italian physicians and foreign students at the University of Padua developed theories that anticipated many scientific innovations of the 17th century (especially with regard to blood circulation). Often they were forced into exile, persecuted by the Inquisition and by political authorities of Protestant territories. In my article, I would like to give an overview of the education and European peregrinations of some of these heterodox physicians, in whose work medical, theological, and philosophical theory, religious dissent, conversion, and exile were remarkably entangled. I will focus on their international correspondence networks and on their relationship with political and religious authorities, with diplomats and with physicians from other confessions.