Flow properties of powders have an important impact during technology processes, especially in case of tableting, where the proper die-filling and constant tablet weight require adequate flow properties of the tableting mixture. Flow properties of different types of fillers, i.e. of mannitol, microcrystalline cellulose and lactose and their realistic mixtures were determined with Carr index, Hausner ratio, Beverloo parameter and with different rotating drum, powder rheometer and Hosokawa Powder Tester PT-X powder flow estimators. With methods used to assess flow properties of powder samples, we confirmed that the ability to flow is better when powder particles are larger and more spherical. It was found that it is not possible to define the flow properties of powder samples in absolute manner, which confirms that the powder flow depends on a number of factors that interact in a complex way. By preparing realistic mixtures for direct compression, we improved the overall flow properties, especially in case of fillers with poorer powder flow. The negative effect of added components on the powder tableting mixture flow properties was found mainly in mixtures based on well-flowing fillers. The most significant changes in results of fillers and their mixtures were demonstrated by the powder rheometer and rotating drum method, and the least by Carr index and Hausner ratio. It was found that one cannot reliably predict the behavior of the tableting mixture only on the basis of predominant component – e.g. fillers. Tablets of different tableting mixtures were pressed in the direct tableting process using a rotary tablet press. The stability of the tableting process was evaluated by assessing the tablet mass variability. We confirmed that the poorer process stability is associated with poorer flow properties of the tableting mixture. The direct tableting process stability was most adequately predicted by the rotating drum method and by powder rheometer, mainly by the rest angle and the cohesion index. Results that were significant for tableting were obtained also with the Hosokawa Powder tester PT-X, mainly by the angle of repose. The Beverloo parameter was defined as the least suitable parameter, mainly due to the inadequacy of the analysis of powders with poorer flow properties.