Our data from studies over many years on upper Tithonian-Berriasian strata of the Crimean Mountains are summarised. Their zonal subdivision has been significantly refined using ammonites and foraminifera, as well as on the basis of calpionellid, ostracod and dinocyst distributions. We have been able to document the presence of all standard Tethyan zones in the Berriasian, i.e., the Jacobi, Occitanica and Boissieri Zones, identified on the basis of foraminifera, ostracods and dinocysts. Based on calpionellids (families Chitinoidellidae and Calpionellidae) in Eastern Crimea, three standard zones were identified: Chitinoidella (Dobeni and Boneti Subzones; Tithonian), Crassicollaria (Remanei and Massutiniana sub zones; Tithonian) and Calpionella (Alpina and Elliptica subzones; Berriasian). Tithonian and Berriasian calpionellid assemblages were identified in Southwestern Crimea. A magnetostratigraphic scale for the upper Tithonian Berriasian has been also developed, thus corroborating a continuous succession of magnetic chrons from M20 through M14. The existence of the M16n.1 r subchron ('Feodosiya') is substantiated; it should be included into the Geomagnetic Polarity Time Scale. The base of polarity chron M18r appears to be the most likely choice among other palaeomagnetic intervals to determine the lower boundary of the Cretaceous System, because it is close to the base of the Grandis Subzone in Tethyan sections and the Chetae Zone in Boreal sections.