Mureş River middle course riverbed dynamics between the Arieş and Strei confluences. The Mureş River is the most eloquent model regarding the alternation of characteristic river courses. In this alternation presents a special interest the course between Arieş and Strei, where due to the morphological and geological conditions we find lower course characteristics. The analysis of the river bed dynamics is carried out in two ways, vertically and horizontally. To evaluate the aggradation and degradation we used hydrometrical data found in the discharge measurements. The difference between the water gage height and the maximum depth indicate the evolution of the thalweg compared to the zero stage of the gage. The analysis of the horizontal dynamics is based on the cartographic method, in which we compare the topographic outlines of the river from three cartographic sources (1911, 1978 and 2005). The horizontal evolution was followed at first on the entire course of the river and then in three separate case studies. The case studies were chosen to illustrate different evolution types of meanders. The significant variations of different morfometrical parameters highlight the lower course character in the analyzed river sector.