This study evaluates effect of metakaolinite on the chemical resistance of standard cement mortars produced from portland cements of different calcium aluminate content, ranging from 3.3% to 11.4%. The metakaolinite was produced by burning of kaolin clay at different time and temperatures, specially selected to ensure the highest pozzolanic activity, as measured by ASTM method. The chemical resistance was evaluated through the measurements of strength, shrinkage and expansion tests on the samples stored in water and chemical solutions. The porosity and microstructure was also investigated. As it appeared, the metakaolinite admixture did not change substantially the standard properties of mortars, though their chemical resistance was markedly improved.