Phase equilibria in Ti-rich corner of the Ti-Si-Sn-Al system were studied using differential thermal analysis, X-ray diffraction, microscopy, and electron microprobe analysis. Projections of solidus and liquidus surfaces, an isothermal section at 1300 degreesC and an isopleth at 9Si-1Sn (at.%) were constructed. It was shown that in the concentration interval studied at the solidus and 1300 degreesC temperatures two two-phase Ti-5(Si,Sn,Al)(3) + [beta -Ti] and Ti-5(Si,Sn,Al)(3) + [alpha -Ti] regions are present. The liquidus surface is characterised by the regions of beta and Z primary crystallisation, resulting in bivariant L <-> beta + Ti-5(Si,Sn,Al)(3) eutectic. The character of horizontal and vertical sections is similar to that for the Ti-Si-Al system.