The paper deals with the stratigraphy of Late Permian and Early Triassic strata of the Luka section in the iri area of western Slovenia. This is the only section presently known in the External Dinarides where the Permian-Triassic boundary is defined following international criteria based on the first appearance of the conodont Hindeodus parvus. The following lithostratigraphic units have been formalized: the Bellerophon Limestone and Evaporite-dolomite Members of the Bellerophon Formation and the Luka~ Formation with the three members,the Transitional Beds, Streaky Limestone and Carbonate-clastic Member. The paper presents the results of micropaleontologicalstudy based on foraminifers and conodonts as well as petrographic and sedimentologic research results. The investigation of conodont assemblages enabled the conodont biozonation of the Permian-Triassic interval of the studied Luka section.