The PreCaspian (North Caspian) Basin is located on the SE margin of the Russian Platform, and extends as far south as the north coast of the intra-continental Caspian Sea. Regional surface elevations here are as much as 24 m below sea-level. The basin is one of the World＇s deepest, with basin-fill sediments exceeding 20 km in thickness. The Proterozoic section, the pre-salt Palaeozoic section, and the Upper Permian (salt-bearing) interval are all about 5-km thick, although as a result of salt movements, the salt-bearing sequence may be thicker. The basin has a roughly oval outline, and is 900-km wide, 600-km in length, and covers around 500, 000 sq. km. It is divided into the Central and SE Subbasins by the approximately east-west trending Astrakhan-Aktyubinsk system of basement highs. A series of massive carbonate build-ups rim the basin margins. This paper considers the structure and hydrocarbons potential of the pre-salt (Palaeozoic) sedimentary section, whose regional prospectivity has been confirmed by the discovery of a series of ＇＇giant＇＇ oil, gas and condensate fields, including Tengiz, Karachaganak and Astrakhan. Hydrocarbons in these fields are sourced and reservoired in massive organic-rich carbonates of Palaeozoic age.