The investigation of as-cast quenched Ti–18Nb–$x$Zr–1Si alloys containing zirconium from 2 to 8% wt. is carried out. The influence of zirconium and quenching temperature at the structure and hardness is studied. The zirconium alloying has the modifying effect at the structure of as-cast alloys: there is some decrease of the heterogeneity and grain size with the increase of its content. As shown, the structure of different morphology and dispersion is formed at the quenching of Ti–18Nb–$x$Zr–1Si ($x$ = 2–8%) alloys depending on the temperature. In the alloys with low zirconium content $\leq$ 2% wt. coarsely lamellar $\alpha ^{''}$-phase is formed that is similar to the martensite in Ti–18Nb–1Si alloy, while a higher content of Zr contributes to the transition to a finely dispersed lamellar or needle form of martensite. According to X-ray microanalysis, the (Ti, Zr)$_3$Si and (Ti, Zr)$_5$Si$_3$ silicides are present in the alloys, the amount of which also depends on the content of zirconium and the temperature of quenching. The maximum hardness in Ti–18Nb–$x$Zr–1Si alloys is achieved with the content of Zr $\cong$4–6% wt. and quenching temperatures of 1100–1200°C.