Bituminous mastics are a blend of bitumen and the finest mineral particles which have the role of filling the voids created by the coarse mineral aggregates. The rheological properties of the mastic phase have a determinant effect on the mechanical behavior of the whole asphalt and can be evaluated in the light of tests recently developed for pure and modified bitumens. The objective of this research is to evaluate the effects of different filler/bitumen ratios and two bitumens grades (50/70 and 30/45) on rheological properties of bituminous mastics associated with permanent deformation and fatigue cracking. The original samples were subjected to short-and long-term ageing according to standard procedures using a rolling thin film oven and a pressure ageing vessel. The short-term aged samples were submitted to the MSCR test and the long-term aged samples were submitted to the LAS test. The MSCR test was performed at 52, 58, 64, 70 and 76°C in order to cover a wide range of temperatures where permanent deformation can occur. The LAS test was run at 25°C, which is a typical temperature where fatigue cracking appears in the asphalt. The overall conclusions are: (i) the filler/bitumen ratio are responsible for an expressive increase in the resistance of the asphalt to the accumulation of plastic deformations and these positive effects are more expressive when a harder bitumen is used; (ii) in the light of the af parameter, obtained from the fracture mechanics, the harder the bitumen and the higher the f/b ratio, the higher the tolerance to fatigue damage of the mastics, but, on the other hand, the fatigue life curves, obtained from the continuum mechanics, indicated the opposite, i.e., the harder the bitumen and the higher the f/b ratio, the lower the fatigue life of the mastics. The analysis based on the fatigue parameter of the Superpave specification (G*.sin) is in tune with the results obtained from the analysis of the fatigue life curves.