This paper is concerned with the role of a range of temperatures, which vary a few tens of degrees below and above room temperature in the mechanical and fatigue properties of different metal alloys used in the aircraft industry. Three different alloys were studied: an aluminium alloy (Al 7175), a titanium alloy (Ti6Al4V), and high strength steel (34CrNiMo6). Push-Pull tests (stress ratio R = -1) were carried out from low temperatures, (-100degreesC) to somehow high temperatures (+ 300, 400degreesC), in air. At each temperature, mechanical properties, sigma(y), sigma(u), E, epsilon(r), impact energy absorption curves, and some fatigue properties such as the initiation life, N-i, total life, N-f, and propagation life, N-p, as well as the shape of the propagation curve, da/dN-K-max (K-max maximum stress intensity factor) were assessed. The main feature observed and discussed in this paper is about the existence of a fatigue ductile-brittle transition temperature (FDBTT), parallel to the monotonic ductile-brittle transition temperature (MDBTT), although these transition temperatures are not the same. And what is also interesting is that even on materials without a MDBTT, a FDBTT was observed.