ABSTRACT: Three types of replacement materials were used in manufacturing of some blended cements. The characterization, durability and resistance of these prepared blended cements against sulfate aggressive media were studied. The replacement materials used in this study are metakaolin, sandy clay and limestone. Blended cement mortars were prepared with 15, 20, and 25% mineral admixtures replacement instead of the same percent of cement. The specimens were immersed in 5% magnesium sulfate and 5% ammonium sulfate solutions then compared with the samples dipped in distilled water as reference samples for 90 days curing. The compressive strength and expansion of cement mortars were investigated at different time intervals. The result revealed that metakaolin can be used for resisting sulfate attack without any disadvantages in physical properties of cement. Sandy clay show good results against sulfate attack but causes side effect on physical properties of cement due to its high insoluble residue. However, limestone as mineral admixture not failed to resist o sulfate attack.