The elastic and viscoelastic properties of nylon-6 films with different structural forms and different degrees of crystallinity, obtained by heat setting nylon-6 films at various temperatures, without constraint, have been investigated. The elastic modulus increases with increasing degree of crystallinity. The values of the transverse elastic moduli for completely amorphous and completely crystalline samples have been calculated on the basis of these results. The measurements of dynamic mechanical properties were carried out at two different frequencies, viz., 11 Hz and 110 Hz, over a range of temperature from room temperature to 150°C under ambient conditions of humidity. It is observed that the moisture content increases whereas the glass transition temperature decreases with increasing temperature of pretreatment. The activation energy of the α transition has also been calculated.