Cr was used to replace Nb, Ti, and Zr in a precursor alloy HfMoNbTiZr, and its effect on the microstructure, phase constitution,and mechanical properties of the newly formed alloys were investigated. Microstructural evolutions revealed thata cubic Laves phase emerged regardless of which element was substituted by Cr. The original single-phase BCC structureof the precursor alloy was thus deteriorated and replaced by two BCC and one cubic Laves phases. The formation of theLaves phase and BCC phases increased the strength to 2480 ± 40 MPa in the HfMoNbTiCr alloy, while the net-like structure(Laves phase) impeded the crack extension and compensated for the decreased plasticity due to the introduction of thebrittle-stiff Laves phase. The other two alloys, HfMoTiZrCr and HfMoNbZrCr, possessed lower strengths of 1400 ± 20 and1642 ± 23 MPa and exhibited a completely brittle fracture character, which was attributed to the high volume fraction andthe morphologies of the Laves phase.