With the occurrence of higher and more frequent axle loads on roads, in particular bridge deck slabs are more severely solicitated by fatigue loading. To avoid heavy interventions for strengthening of bridge deck slabs, an improved building material is used, namely Ultra-High Performance Fibre Reinforced Concrete containing steel rebars (=R-UHPFRC). By adding a thin (30 to 50 mm) layer of R-UHPFRC on top of the deck slab, the required fatigue resistance and load carrying capacity may be restored and improved. In addition the R-UHPFRC layer is waterproof which provides improved durability. This paper presents results of fatigue tests for the determination of the fatigue behaviour of reinforced concrete (RC) slab-like beams strengthened with R-UHPFRC leading to RU-RC beams. The experimental results show high fatigue resistance of RU-RC beams indicating a significant potential for strengthening of RC bridge deck slabs. For the application, rules are deduced for the design of the RU-RC member and the corresponding fatigue safety verification. Finally, an application of this novel technology is briefly described demonstrating that improvement of bridge deck slabs using UHPFRC is a relatively gentle intervention with limited intervention costs. There is a potential inherent with this novel construction method to limit the duration of the working site and thus to reduce the user costs as well as life cycle costs.