One property of vanadium-base alloys that is not well understood in terms of their potential use as fusion reactor structural materials is the effect of simultaneous generation of helium and neutron damage under conditions relevant to fusion reactor operation. In the present Dynamic Helium Charging Experiment (DHCE), helium was produced uniformly in the specimen at linear rates ranging from≈0.4 to 4.2 appm helium/dpa during irradiation to 18–31 dpa at 425–600°C in the Li-filled capsules. Results of postirradiation tests of mechanical properties of V-4Cr-4Ti, an alloy identified to be most promising, are presented. Effects of helium on tensile strength and ductility at 420–600°C were insignificant for irradiation at these temperatures. However, postirradiation ductilities measured at 20–200°C were higher than those of the non-DHCE specimens (negligible helium generation), whereas strengths were lower, indicating that different types of hardening centers were produced during DHCE and non-DHCE. Ductile-brittle transition behavior of the DHCE specimens was determined from multiple bend tests on TEM disks and broken tensile specimens. No brittle behavior was observed at temperatures >-175°C. In contrast to tritium-trick experiments in which grain-boundary coalescence of helium is pronounced in the absence of displacement damage, no intergranular fracture was observed in tensile or bend-tested DHCE specimens.