In 1980, the New Zealand Forest Service adopted the Fire Weather Index (FWI) System module of the Canadian Forest Fire Danger Rating System for rating fire danger in exotic pine plantations. In the years that followed, the maximum benefits of what was to become the New Zealand Fire Danger Rating System were never fully realised due to a lack of technology transfer and a failure to adapt it to the local fire environment. After a lapse of 15 years, a fire research programme was re-initiated in 1992 to address these issues. Based on the New Zealand experience, this paper highlights the issues and opportunities associated with the adoption and/or adaptation of overseas fire danger rating systems. Significant savings in the time and cost of development can be made by adopting an existing fire danger rating system. However, predictive errors can result if no effort is made to assess the basic fire behaviour relationships that underpin the adopted system when it is applied to a fire environment that is distinctly different from the one it was designed for. The importance of this validation is illustrated through application of the Initial Spread Index component of the FWI System to the prediction of head fire rate of spread in New Zealand's native heathland fuel complexes.