Abstarct: Abstract Grouted macadam mixtures are composites consisting of cementitious and bituminous phases which are used as pavement surface laxyer due to their favorable advantages such as: bearing high static load, good rutting resistance, good durability and resistance to chemical attacks and fossil fuels. However, these mixtures do not have good performance at low temperatures. Reinforcement by fibers, as one of the known methods to improve the performance of asphalt and concrete mixtures, has the potential to be used to strengthen Grouted macadam mixtures as well. In the present study, fibers produced baxsed on glass (Micro-ocorta) and polypropylene (P.P) materials were used to reinforce the bituminous and cementitious phases of Grouted macadam mixtures, respectively. The bituminous phase of the first group of samples was reinforced with 0.2, 0.4 and 0.6 volume percent of Micro-corta fiber. Also, 0.2, 0.3 and 0.4 percent by volume of P.P fibers were used in the production of cement grout in the second group. In the next step, the performance of each of the mentioned groups was compared with unreinforced samples through low temperature three-point bending and indirect tension strength tests. The results showed that the best low-temperature performance of Grouted macadam mixtures in both indirect tensile strength and three-point bending tests was obtained for mixtures containing the highest percentage of fibers(0.6% of Micro-corta and 0.4% P.P fibers). It was also observed that with the reinforcement of the bituminous phase, the Fracture Strain Tolerance (FST) index in the three-point bending and indirect tension strength tests was improved up to 66.19 and 25.01 percent, respectively. In addition, it was seen that the use of modified cement mortar has increased the FST index in the three-point bending and indirect tension strength tests by 91.87 and 30.9%, respectively, compared to unreinforced samples. Overall, the findings of this study show that the reinforcement of both bituminous and cementitious phases of Grouted macadam mixtures by microfibers can help improve their ability to deal with the occurrence of low temperature cracks.