Even today, leprosy is a relatively frequently occurring disease, especially in tropical regions of the world. From the eleventh to thirteenth century, leprosy pandemics affected Europe, including Croatia. Probably as a consequence of such history, one can still find endemic foci of leprosy in present-day Croatia. The aim of this study was to analyse all cases of leprosy registered in Croatia during the twentieth century ; therefore, we studied thoroughly existing medical documentation and published reports on sporadic leprosy cases, and went on to collect the relevant data through on-site investigation in those parts of Croatia known as putative endemic foci of leprosy. In this way, we collected data concerning the number of leprosy cases, the probable sources of infection, and traced the possible paths of spread of the disease. During the twentieth century, 17 cases of leprosy were registered in Croatia. However, due to the loss of medical documentation concerning the cases from Metković, the total number was obviously slightly greater. Concerning the 17 analysed cases, 4 patients were most probably infected during their visits (as sailors or immigrant workers) to the Middle East, South America or Africa ; 3 patients developed leprosy after prolonged close contact with previously infected family members, while the exact source of infection remains unsettled for the remaining 10. However, 2 of these patients originated from the area of Cazin in Bosnia and Herzegovina, which is known to be an endemic focus of leprosy. Furthermore, the remaining 8 came from the small area of the village of Blizna in the Croatian municipality of Trogir, and therefore it seems reasonable to conclude that Blizna represents the endemic focus of leprosy in Croatia. The last case of leprosy in Blizna was registered back in 1956. Nevertheless, it is clear that sporadic cases of leprosy can reappear in Croatia, originating either from this endemic focus of Blizna, or as an infected person returning to Croatia from abroad. So, we can conclude that, even today, Croatian medical doctors (and especially dermatovenereologists) should still be acquainted with the clinical diagnosis of leprosy and basic principles of its treatment.