The influence of different types of supplementary  materials (limestone filler, slag and natural pozzolana) on the acid corrosion resistance of hardened mortars based on portland cements was assessed in this paper. The corrosion products were studied by thermal analysis, microscopy (SEM&EDX) and X ray diffraction analysis. The compressive strength and weight loss of the mortar specimens, immersed up to one year in hydrochloric acid solution (0.5M), show that blended cement with slag and natural pozzolana additions performed better than the blended cement with limestone filler and normal portland cement.