After a discussion about different models on bonded composite connections reported in the literature, the paper presents the results of an experimental investigation on static and fatigue behaviour of bonded composite joints. A careful damage evolution analysis identifies in crack initiation and in its
subsequent propagation in the adherend/adhesive interface the mechanism controlling the high cycle fatigue strength. It has been found that the fraction of the life spent in the crack initiation is not lower than 25% of total fatigue life.