The Dalmatian barbelgudgeon (Aulopyge huegelii, Heckel, 1843) belongs to the family Cyprinidae and is the only member of the genus Aulopyge. This species is endemic to the Adriatic Basin, and can be found in the Croatian rivers Cetina, Krka and Čikola. The aim of this study was to obtain previously unknown information on reproduction of this endangered species, using a combination of morphometric and histomorphometric measurements and gonadosomatic index. The specimens were collected in the rivers Krka and Čikola, a total of 29 male and 57 female individuals. Females reach greater body length than males (average standard body lenght for males was 103,93 mm, and 112,71 mm for females). The highest measured body weight for males was 47,60 g and 53,74 g for females. Gonadosomatic index was calculated and its values reach maximum in April, then gradually decline to July. Histomorphometric analysis of testes showed that all analysed males were sexually mature. Size of the eggs in the ovaries was measured and the number of mature eggs was determined. Fecundity of one spawning ("batch fecundity") was calculated and it was in range from 68 to 1154 mature eggs. Mature eggs were only found in females captured from April to July. The results show that the reproductive cycle of this species begins in April (at temperatures of about 12 ° C) and lasts until the end of July. The results of this study can be used in the planning of science-based protection of this species in regional karst rivers and lakes.