Had the Muslim conquest an impact on the population of the Byzantine Empire? This paper is an attempt to visualize the demographic consequences of the loss of the Eastern provinces, with a special interest for the migrations from the caliphate to the Empire and especially to Constantinople. The sources are scarce and give only punctual information on forced transfers of population from conquered areas, on some people going on purpose in exile inside the Empire, and on individual destinies of some renegades. As usual, the sources are more numerous about the clergy and show a continuous flow of exiles from the Anastasis in Jerusalem to Constantinople and St-Sophia.[fr] Cet article est une tentative pour mesurer les conséquences démographiques...