ABSTRACT: One of the problems concerning contemporary facing walls is a decrease in their aesthetics due to discoloration. Besides the quality of workmanship, the use of mortars containing lime is wrongly regarded as the main cause of this phenomenon. However, one should note that regardless of the applied system of a masonry element (namely mortar), efflorescence with different intensities and chemical compositions appears in the majority of new structures within the first few years of their use. The purpose of the study was to investigate the impact of mortars on the formation of efflorescence of facing walls and to establish factors limiting its occurrence.