An increasing number of wind turbines are being incorporated into electrical networks. In some countries they are becoming a key part of the distribution network & as such affect the overall system performance & reliability [1]. The configuration, technology & size of wind turbines have been changing rapidly over the last few years & larger turbines, >=3D2MW, incorporating this new technology are being installed onshore throughout Europe. The potential for more wind turbines to be erected in remote locations & offshore, to achieve a greater wind energy harvest, is heightening the need for accurate reliability prediction so that network reliability calculations can be done & wind turbine life predicted. This paper concerns a reliability modelling problem that has arisen when analysing the Failure Rates of wind turbines in Denmark & Germany, using data collected from Windstats [2] over the past 7 years. One of the authors has also shown [3] that such data can be used to predict the reliability of future equipment.