This paper summarises the results of a reliability assessment for a deepwater, Gulf of Mexico FPS mooring design. The reliability of single components (chain and wire rope segment) on the most loaded line is established using a second moment reliability method. These results are then used to extend the analysis to multiple failure points along a single line and failure of multiple lines. The major objectives of this study are (1) to assess the impact of the mooring line tension criteria given in the draft API Recommended Practice for FPS Moorings and (2) to compare the mooring system reliability resulting from these criteria with more conventional platforms such as steel piled jackets (SPJ). Only failures associated with line breakage due to overload are considered. Potential failure modes such as anchor slippage, line fatigue and failures at terminations or connections are not included. The calculated system reliability or the specific semisubmersible type FPS analysed, considering only line breakage as a failure mechanism, is found to be of the same order of magnitude as that typically calculated for collapse due to overload of SPJs. This provides a measure of confidence in the criteria for allowable line tensions outlined in the new RP-FPS.