The phenomenological and structural aspects of biaxial drawing of a vinyl alcohol-rich ethylene/vinyl-alcohol copolymer is studied as a function of temperature. For draw temperature above the crystalline mechanical relaxation, T-alpha, sharp necks accompanied with catastrophic fissures develop during simultaneous biaxial drawing as well as in the first step of sequential biaxial drawing. For draw temperature below T-alpha, simultaneous biaxial drawing can be successfully achieved via propagation of diffuse necking so that a minimum macroscopic draw ratio of about 3 x 3 is required to obtain a uniform plastic strain. The strong interaction anisotropy of the sheet-like structure of the monoclinic phase is responsible for the fissuring trend at T > T-alpha. In contrast, the isotropic mesomorphic phase that is strain-induced at T < T-alpha enables simultaneous biaxial drawing. The development of a planar texture suggests that the transformation results from transverse crystal slip. However, the random distribution of the H-bonds in the mesomorphic phase is rather consistent with an accumulation process of conformational defects that remain frozen in the crystal.