Multicomponent alloys based on the Ti-Si system are attractive structural materials with high oxidation resistance and high temperature strength. Zr is one of the elements that may further improve these properties, but there is little systematic information about the combined influence of Si and Zr in wide concentration ranges on the structure and mechanical behaviour of titanium and titanium-aluminium alloys. The features of structure, phase composition, and mechanical properties of as-cast Ti-3Al-XSi alloys (where X=2,4,6-wt.%) vs. Zr content (0-18-wt.% ) have been studied in the present work. It is shown that Zr additions promote essential refinement of alloy microstructure and the formation of ternary (Ti,Zr)2Si silicides. It was found that hypoeutectic Ti-3Al-(4, 6)Si alloys with high Zr content have very refined microstructures based on an α-Ti+(Ti,Zr)2Si eutectic. Such alloys demonstrate high strength at room temperature and up to 400°C. Hypoeutectic alloys with 5-wt.% Zr reinforced by eutectic Ti5Si3 silicides are characterised by higher strength in the temperature range from 400 to 600°C.