Viscoelastic relaxations of three samples of vinyl alcohol-ethylene copolymers, richer in the former comonomer, were studied in a wide range of temperature. The temperature location, intensity and apparent activation energy of the distinct relaxations found are discussed and compared with those of the homopolymers, poly(vinyl alcohol) and polyethylene. Differential scanning calorimetry and X-ray diffraction results of the specimens are also discussed in the frame of the dynamic mechanical analysis, showing that the polymorphism exhibited in some copolymers is a result of the thermal treatment.