The effect of minus No. 200-sized material (mineral filler) on the fundamental mechanical properties of hot-mix asphalt is not well understood. In the work reported in this paper a series of minus No. 200 (75 μm) mineral fillers were used to prepare and characterize filler-asphalt mastics and hot-mix asphalt concrete. The mineral fillers were blends of dust of fracture and baghouse dust was sampled from seven sources. The gradation and the void-filling characteristics of the mineral fillers were determined. Mastics prepared with the fillers were characterized with viscosity measurements at 60°C (140°F) and dynamic mechanical properties, storage modulus, loss modulus, and tan delta, over a wide temperature range. Mixtures containing the mineral fillers were prepared using several different filler-asphalt ratios. Originally, the behavior of the mixes was to be evaluated with a fatigue test in which a test beam is supported on an elastic (lowmodulus rubber) foundation. This test method proved unacceptable because the failures that occurred were in shear rather than bending fatigue. As an alternative, the single-edge-notched-beam (SENB) fracture toughness test was used. With this procedure it was possible to determine the fracture toughness of the mixes as a function of temperature. The source of the mineral filler, as reflected by the properties of the mineral filler-asphalt mastics, was correlated with the fracture toughness properties of the mixes.