Ultra-high　performance　concretes　(UHPC)　are　advanced　cement-based　materials　characterised　by　superior　mechanical　properties　with　respect　to　normal　and　high-strength　concretes;　however,　their　dense　and　compact　matrix　can　facilitate　the　onset　of　spalling　at　high　temperatures.　This　problem　is　often　coped　up　by　adding　polypropylene　(PP)　fibres　to　the　mix　design,　alone　or　with　other　types　of　fibres;　steel　fibres　enhance　the　material＇s　tensile　capacity.　The　paper　presents　a　series　of　tests　on　two　UHPC　types　(150　and　180　N/mm2)　with　PP　fibres　(0.27%　of　volume)　and　variable　content　of　steel　fibres　(0%　to　1.92%),　aimed　at　investigating　the　residual　mechanical　properties　of　the　material　after　high　temperature　exposure.　The　experimental　results　are　compared　to　available　research　on　small　UHPC　specimens　exposed　to　high　temperatures,　with　dosages　in　PP　fibres　from　0.03%　to　2%,　and　in　steel　fibres　from　0　to　3%.　The　results　of　this　research　demonstrate　that　UHPCs　need　hybrid　fibre　reinforcement　(PP　+　steel)　to　withstand　high　temperatures,　and　that　the　residual　strength　increases　after　200　°C　exposure,　at　all　steel　fibre　dosages;　this　is　in　line　with　literature.　Available　research　also　shows　that　strength　loss　is　possible　in　hot　conditions,　as　found　in　the　present　research,　while　PP　fibres　alone　do　not　always　prevent　the　occurrence　of　spalling　in　small　UHPC　samples.　©　2021　The　Author(s)