In recent years, Belgium and the Netherlands have been confronted with relatively many citizens or residents who have traveled to Syria and Iraq to join and fight with jihadist groups — 388 Belgian and 220 Dutch as estimated by the respective authorities. This article provides an overview of the phenomenon of jihadist foreign fighters in the Low Countries, analyzing their characteristics, motivations, and roles in the war in Syria and Iraq. It compares the Belgian and Dutch cases, focusing on key aspects, such as age, sex, and geographical and socioeconomic background.