ABSTRACT: The updated conodont zonation for the Serpukhovian, Bashkirian, and Moscovian stages of Ukraine presented here is the result of long-term studies of the Carboniferous conodonts in the Donets Basin, Dnieper-Donets Depression, and L'viv-Volhyn Basin. The detailed investigations were mostly conducted in the nearly complete, well-exposed Carboniferous succession in the Donets Basin, which has been regarded as a standard for the Carboniferous System. Three conodont zones are distinguished in the Serpukhovian Stage. The earliest Serpukhovian zone, the Lochriea ziegleri Zone, is defined in the Dnieper-Donets Depression and in the L'viv-Volhyn Basin and is correlated with the Cavusgnathus naviculus Zone of the shallow-water to coal-bearing units of the Donets Basin. Species of the Gnathodus bilineatus group, which dominate late Mississippian conodont faunas in Ukraine, are used to subdivide the upper Serpukhovian and correlate it to other areas. The dominant species of Idiognathoides and Declinognathodus provide the conodont zonation for the Bashkirian and the earliest Moscovian. The lower Bashkirian boundary,which is the boundary between the Mississippian and Pennsylvanian subsystems, is defined in the Donets Basin and Dnieper-Donets Depression by the FAD (first appearance datum) of Declinognathodus noduliferus. Six Bashkirian and one Moscovian zones comprise, in ascending order, the Declinognathodus noduliferus, Idiognathoides sinuatus-Id. sulcatus sulcatus, Idiognathodus sinuosus-Id. sulcatus parvus, 'Streptognathodus' expansus, Id. tuberculatus-Id. fossatus, Decl. marginodosus, and Decl. donetzianus zones. The proposed base of the Moscovian Stage is the FAD of Decl. donetzianus in the Donets Basin. Above this level, species of Neognathodus, 'Streptognathodus' and Idiognathodus comprise two currently recognized zones, the N. atokaensis-'Streptognathodus' transitivus and I. izvaricus zones. Species of Swadelina provide the basis for zonation of the late Moscovian in the Donets Basin: in ascending order, the Swadelina dissecta, Sw. gurkovaensis, and Sw. subexcelsa zones. The most significant levels for correlation to other Carboniferous basins are the lower boundaries of the Lochriea ziegleri Zone (= Visean/Serpukhovian boundary), Decl. noduliferus s.l. Zone (= Serpukhovian/Bashkirian boundary), Decl. donetzianus Zone (= Bashkirian/Moscovian boundary) and Idiognathodus sagittalis-I. sp. A Zone (= Moscovian/Kasimovian boundary).