Limestone has been used as a partial substitute for cement, due to its beneficial effect on mechanical properties of mortars and concretes. In the present research, we studied the effect of the mineralogical composition in mortars produced from limestone samples collected in different areas of Mozambique, using two cement types (Portland cement 32.5N and 42.5N). Additions of 10 to 25% limestone gave, in general and for the 32.5N cement, good results of the compressive strength for all limestone samples, while for the 42.5N only the Massinga samples performed well. Effect of the limestone additions on the flexural strength showed a beneficial effect for all samples and at all compositions studied, when using the 42.5N cement, while for the 32.5N cement only additions of 10% limestone gave values of the flexural strength higher than the reference material, with the exception of the Magude samples.