This paper address the topic of application of MEMS inertial and magnetic sensors for direct determination of exterior orientation parameters of acquired images. First the role that MEMS inertial units currently play in the spatial information acquisition technology is characterized. Besides basic mathematical formulas describing the dependencies between inertial measurements and orientation parameters of optical sensors, especially cameras, are given. The test measurements were conducted using the photogrammetric system prototype consisted of the digital camera, GPS set and MEMS IMU. During the tests the measurements in static and dynamic conditions were carried out. Subsequently the inertial measurements were used to determine exterior orientation parameters of acquired images. The obtained results show that relatively high errors affect the determined azimuth of camera axis. The errors of other two angles, that parameterize the rotation matrix, are smaller. The potential sources of errors may be connected mainly with imperfections of system construction and instabilities of the Earth magnetic field. In order to improve the acquired accuracies, further integration of inertial measurements with photogrammetric and GNSS observation can be carried out. Further development of MEMS technology may provide the possibility of constructing more accurate sensors so that they can be shortly concerned as parts of commercial mobile mapping systems.