The repair welding of aluminum alloy 5083 was studied using Gas Metal Arc welding (GMAW) process. The effect of heat cycles from welding was investigated in some details. Butt joints of 6 mm and 3 mm thick were welded with 5356 filler metal. Then weld was removed by grinding and repeatedly welded again for 2 times. After each repair weld, the weld was assessed by macrostructure, microstructure and mechanical tests. The results revealed porosities of all weld samples. The repair welds indicated lower tensile strength compared with the new welds. In addition, all tensile strengths were much lower than the base metal. All samples were fractured at the weld metal.