Mechanical properties after neutron irradiation at temperatures around 400°C of the V-Ti-Cr-Si type alloys were reported. Neutron irradiation was carried out at temperatures 374 °C and 406 °C with fluence of about 7 and 50 dpa, respectively. Tensile tests were conducted using miniaturized specimens at ambient temperature and irradiation temperature. Uniform elongation of the alloy V-5Ti-5Cr-1Si-1Al-1Y (nominal weight percentage) was maintained at about 4.2 and 5.9% after irradiation and testing at 374 and 406 °C, respectively. Increases in yield stress were 240 MPa and 160 MPa, respectively. Although the irradiation hardening was large, apparently smaller than that of V-Ti-Cr type alloys without Si, Al and Y additions, it was possible that the additional elements reduced the concentration of interstitial impurities in solution, which caused high irradiation hardening. It was found that a small addition of Si, Al and Y showed possible improvement in the ductility at lower temperature irradiation of vanadium alloys.