Materials applied for components in gas turbines have to provide good oxidation behavior, high melting points and outstanding specific mechanical properties. Al-containing refractory high-entropy alloys are expected to combine those requirements. Regarding thermodynamics, the recently developed high-entropy alloys are likely to form a solid solution and therefore possess favorable properties such as a severely distorted lattice and, thus, significant solid solution hardening. We present a 5-component high-entropy alloy, namely the equiatomic Nb-Mo-Cr-Ti-Al. After arc melting, a quasi-homogeneous microstructure was achieved by heat treatment at 1300 °C for 20 h. Mechanical properties at high temperatures were characterized by compression tests ranging between 800 °C and 1200 °C. The altering of the microstructure during deformation was investigated by SEM and EBSD. These changes reveal the underlying deformation mechanism. In addition, the impact of the number of elements and, thus, changing atomic size differences on these mechanisms were analyzed by modified 4-component (e. g. Mo-Cr-Ti-Al and Nb-Mo-Ti-Al) and 6-component (Zr-Nb-Mo-Cr-Ti-Al) alloys.