Genus Delminichthys includes four endemic species from Croatia and Herzegovina: Delminichthys ghetaldii, D. adspersus, D. jadovensis and D. krbavensis. Objectives of this research were to get a new cognition about the morphology of the species and establish morphological differences among different populations. The research was conducted on eight rivers and springs: Jadova, Vrljika, Matica, Prološko blato, Krbava, Ombla, Dabarsko polje and Fatničko polje. Morphological analyses encompassed study of morphometric, meristic and phenological characters. Morphometric characters were analysed with various statistical methods. Obtained data were compared with results from previous research. The most important deterministic attributes are: groove behind upper lip, eye diameter, number of pored scales along lateral line, mouth position and number of branched rays in pectoral fins. Morphology mostly confirms existing classification, with some difference between populations of the same species within D. adspersus and difference between population in Ombla and other D. ghetaldii populations (in subterminal mouth, lack of body pigmentation and uniform dark spots on the back and flanks). Present key for determination of Delminichthys species is valid, with some minor corrections in number of pored scales range and adding the number of branched rays in pectorals fin as additional diagnostic attribute.