The fatigue behavior of an isotropic conductive adhesive made of epoxy matrix with silver flakes is studied by performing fatigue tests. Repetitive tensile and compressive strains are applied to the conductive adhesive while the electrical resistivity is constantly monitored in situ. It is found that resistivity of the conductive adhesive increases as more fatigue cycles are applied. The electrical resistivity may increase by more than 100% before any visible fracture of the sample can be observed. Based on 100% increase of the resistivity as the electrical failure criterion, the strain amplitude versus number of cycles to electrical failure data can be fitted to a power law model. Experimental results also show that strain amplitude, strain ratio and strain rate all have an effect on the electrical fatigue life of conductive adhesives. Microscopic images of the failed conductive adhesive samples show that electrical failure is caused by the debonding of silver flakes from epoxy matrix. Further examination shows that the debonding typically occurs along the direction of the maximum shear stress. (C) Koninklijke Brill NV, Leiden, 2008.