Abstract: The current work reports 28 species of crustaceans from the karstic groundwaters of Vitosha and Golo Burdo mountains, including 9 cyclopids, 15 harpacticoids, three amphipods and one syncarid. Their spatial distribution relating to the hydrogeological characteristics of the karst are analyzed. Fourteen species are found in the infiltration zone. The highest species richness is established in the source “Popov izvor” — 9 species, three of which are stygobiontic. This source gives us natural access to the saturated zone of the karst. The differences in the species composition of the studied region with the karstic system of Ponor Mountain (Western Stara Planina Mountain) are analyzed.