The Heusler alloys based on Ni2MnGa are considered as promising new multifunctional material showing magnetic shape memory effect related to the giant magnetic field induced strain in martensitic phases. The observed properties are determined by the martensitic transformation induced by temperature change consisting of a lattice deformation of the parent cubic phase. Some distorted martensites are characterized by incommensurate modulation and their crystal structures have been recently solved by Rietveld method. In Ni-Mn-Ga alloys it is also possible to induce martensitic transformations under mechanical stress with corresponding structures showing structural modulation. Therefore we propose to investigate martensitic transformations in Ni2MnGa under uniaxial compression in order to compare the main features of the temperature and stress induced martensitic crystal structures.