This paper presents the definition of lower deck elevation (LDE) of fixed offshore platforms in Mexican part of the Gulf of Mexico (GoM), which were applied in the Mexican code for design and assessment of fixed offshore structures NRF-003-PEMEX-2007. This was obtained as a result of a decision methodology developed here, an optimization algorithm composed of an objective minimization function subject to a safety restriction and by the application of a set of real structural maintenance and equipment replacement costs. Platform projected service life dependent total costs of LDE contemplate expected costs of structural and equipment maintenance after the occurrence of tropical cyclones and northers, and the expected cost of equipment mobilization. This work regards a group of offshore platforms in the Bay of Campeche whose elevation lies between 15.85 and 19.10 m above mean sea level, as well as recent metocean hazard information. Similar expected values of total costs due to maintenance and repair were obtained, while safety constrains demand the LDE not to be less than +19.10 m.