Reliable and long-term wave data are essential for the design of almost all coastal and marine structures. In this study, the wave climate along the Turkish coasts was derived based on a century long data of European Centre for Medium-Range Weather Forecasts. For this purpose, firstly, the data set was calibrated and verified by using satellite and in-situ measurements. Then the design waves corresponding to different return periods were determined by extreme statistics. Therefore, a new and reliable design wave height data along the Turkish coasts have been provided for the designers and applicants. Results were compared with Wind and Deep Water Wave Atlas Along the Turkish Coasts (Ozhan and Abdalla, 2002). The comparison results indicate that the design wave heights provided by the Atlas are higher than the current study, especially in the Aegean Sea. Moreover, the effect of theoretical distribution function and the data number were investigated on the design wave height. Design wave heights were recalculated by best fitting distribution function and it was shown that distribution function may affect the design wave height. It was also concluded that when the wave data used in extreme value analysis was less than 30 years, the error increased in the estimation of the design wave height with both 50 and 100 years return periods. Besides, by using calibrated and the verified century-long wave climate data it was shown that there was an increasing trend in the annual mean and maximum wave heights along the Turkish coasts.