The microstructure and mechanical properties of AA5083 aluminum alloy sheets consisting of well developed β-fiber texture were investigated. In order to maintain rolling textures after final annealing, the materials were rolled isothermally at 623 K by making use of heated rolls and reheating process every pass up to final thickness of 1 mm. The isothermal rolled sheets consisted of fine subgrain structures through the thickness with a high proportion of low angle boundary less than 15°. Tensile properties showed anisotropy clearly regarding elongation and Lankford value. In the isothermal rolled sheets, the elongation of 0° to rolling direction was below 20% and Lankford value of 45° to rolling direction was over 1.5. Therefore, the average Lankford value showed 1.0. The yield strength of the isothermal rolled sheets was about 40% higher than that of the cold rolled sheets because of subgrain structures. The low ductility of 0° to rolling direction on the isothermal rolled sheets seemed to reduce drawability at room temperature. The warm drawability of the isothermal rolled sheets improved and was superior to the cold rolled sheets because of increasing ductility and keeping higher strength than the cold rolled sheets.