The objective of the Joint Industry project ‘FPSO Integrity’ is to provide insight in the fatigue loading of FPSO’s and the accuracy and validity of computational models. The results should contribute to reliable life time prediction and site assessment studies for this relative new concept of production. Within the frame work of this JIP, ‘Glas Dowr’, a new build double hull FPSO operated by Bluewater for Amerada Hess at the Durward and Dauntless fields in the North Sea, has been instrumented extensively. The objective of the instrumentation was to measure sufficient signals to derive the fatigue loading on the vessel. The dedicated monitoring system comprised the instrumentation of two cross sections of the vessel with strain gauges, pressure transducers and wave height radar’s. Also the deck and the turret were equipped with strain gauges. Both the wave induced motions and the low frequency positions and orientation of the vessel was recorded. For the analysis of the measured signals the wind, wave and current conditions have been recorded as well as the vessel parameters such as draft, trim and tank loads. Data from the Glas Dowr has been collected from October 1, 1997 to 1 August 1999. The data has been subjected to long term statistical analysis and for selected periods to more detailed spectral and statistical analysis as well as rain flow counts. The results have been used for validation of existing fatigue load calculation methods used by five classification societies and for the development of new fatigue load prediction software.