Abstract The ISO 19900 series of international standards comprises different levels of standards, ISO 19900 giving General Requirements for offshore structures, ISO 19901 giving Specific Requirements for various aspects of offshore structures that have relevance to different types of offshore structure (in several parts), and then a series of standards giving requirements for the different generic types of offshore structure. Of this last category, three have now been published; ISO 19902 for Fixed Steel Offshore Structures, ISO 19903 for Fixed Concrete Offshore Structures, and ISO 19904-1 for Floating Offshore Structures. The development of these three International Standards is described in this paper, which gives details of the scope, provenance, key features, contents, and organization of each of the three standards. ISO 19902 is a development of API RP2A LRFD, but in the preparation of the International Standard a number of research and Development Joint Industry Projects (JIPs) were commissioned, and the enhanced knowledge from these projects, together with knowledge and experience from the offshore operating areas around the world, have been incorporated. ISO 19903 is a new and somewhat different standard, as it deals with the entire task of engineering a concrete offshore platform facility, with mechanical systems, etc., rather than just the detailed design of its concrete members. To a large extent the standard relies on the existence of national or regional standards for design of concrete structures that can be safely used in an offshore concrete structure, as such structures can range from quite simple to really sophisticated structures. ISO 19904-1 is a new standard entirely. It is based partly on API RP 2FPS, which was developed in the same timeframe, but includes concepts taken and harmonized from North Sea practice represented by then HSE and NPD guidelines and from class rules. Some text was written specifically for this standard, particularly the clause on structural integrity monitoring and various sub clauses elsewhere that represent lessons learned in from industry experience during the period in which the standard was written.