© Published under licence by IOP Publishing Ltd.This study focuses on the static and fatigue strength analysis of the existing 5-m RUZGEM composite wind turbine blade with and without defect in the form of debonding. Puck progressive damage analysis is used to investigate the effect of defect introduced to the spar/pressure side interface on the ultimate strength under extreme flap-wise (min) by single-loading point application. In addition, fatigue life according to the Germanischer Lyod (GL) guidelines is determined. For the original blade, collapse is observed after 85% loading, whereas due to defect, failure region changes and the blade collapses after 69% loading. Blade is found to exhibit sufficient resistance against fatigue. However, the inclusion of defect decreases the fatigue life of the blade significantly.