The main difference between normal mortar and polymer modified mortar is the microstructure. Whereas cement is the only binder in normal concrete, the binder of PCM contains cement and polymer. It is known, that these polymer modified cementious matrixes show a higher shrinkage than the non-modified ones. But it is also known, that the PCMs show fewer cracks due to shrinkage. A lot of different investigations have been carried out to find the reason for this con-tradiction. The measurement of shrinkage of PCMs and polymer modified cement stones will be presented in this paper. The prisms were stored under various climate conditions and show a varying shrinkage accordingly. Taking these results into account it becomes obvious that the shrinkage of PCMs depends considerably on the hydration shrinkage, to a lesser extent on the drying shrinkage. Furthermore, a model experiment as to the adhesive bond of cement stones compared to natural stones was introduced.