<p>A cost analysis of the failure consequences, for an offshore platform with very high level of oil/gas production, is conducted to assess its relevance on the target reliability index. There are no cost functions for the losses components for specific platform structural types and the production volume handled by the platform. In this paper, cost functions are developed for the considered consequences of the platform failure: replacement, environmental, deferred production and life loss. Empirical relationships for the weight of structural members are derived as a function of the water depth and a cost of reliability function is built for the hurricane hazard level of the platform location. The deferred production loss considers the volume of production and the international current prices of oil and gas. A sensitivity analysis is performed for various values of these prices, the production volume and the net annual interest rate. For the case study, the environmental loss is the highest cost component (50%) of the total losses and the target reliability index is 3.13. The platform has a reliability index of 4.6 well above the target value.</p>