The paper presents research of durability (static long-lasting life and fatigue life) of selected adhesive composites Belzona, which are epoxy adhesives physically modified with metallic and ceramic fillers. The tests were conducted by determining creep curves, short-term strength of lap joints, static long-lasting life of adhesive joints and adhesive composites. Numerical calculations, conducted with the Finite Element Method, were made in order to explain (on the basis of distribution of stress and strain) the phenomena occurring during a long-term load of an adhesive-bonded joint, which are unobservable during experimental research. With regard to comparative analysis' needs, the research results gained for Belzona composites were compared to the results gained for an adhesive based on physically unmodified Epidian 57 epoxy composition hardened with triethylenetetramine (Epidian 57/TETA).