Powder metallurgy molybdenum (PM-Mo) and electron beam melted molybdenum (EB-Mo), which were annealed at 1173K and recrystallization temperature 1573K, were neutron irradiated in JMTR at 1073-1453K to fluences of 1.8-5.2×10^n・m^ and then deformed in tension at room temperature. Elongation for EB-Mo annealed at 1173K and irradiated at each temperature was larger than that for unirradiated EB-Mo. For PM-Mo annealed at 1173K, elongation was reduced by irradiation at high temperature and the yield stress was lower than that for unirradiated one. It is suggested that grain boundary effects will affect irradiation embrittlement. The correlation between uniform elongation, yield stress, fracture stress and total elongation was illustrated
