The plastic behavior of polyamide-g (or nylon-6) films under uniaxial and biaxial tensile drawing is studied in relation to structural features. Quenched films in the mesomorphic beta form are more ductile than films in the predominant: stable alpha form. Films in the major gamma crystalline form are intermediate between films in the beta and alpha forms. Under uniaxial drawing, a great part of the beta phase undergoes strain-induced phase change into the alpha form, involving strain hardening of the material. The beta --> alpha phase change is more pronounced above 120 degreesC because of additional thermal reorganization. The gamma form that is thermally stable up to 200 degreesC also undergoes a strain-induced phase change above 120 degreesC, but the reorganization is much less important than for the beta phase. Biaxial drawing can only be achieved below 120 degreesC with quenched Rims. This is likely due to the high mechanical anisotropy of the H-bonded sheetlike structure of both the alpha and gamma phases that is suspected to develop catastrophic splitting under a normal stress component, notably above 120 degreesC because of the collapse of the paraffin-like van der Waals interactions between the sheets. The disordered distribution of the H bonds in the mesomorphic beta structure of the quenched films is more appropriate for biaxial drawing. The strain-induced beta --> alpha phase reorganization, which might have been a serious prejudice, proved to be much reduced during biaxial drawing below 120 degreesC. The mechanism of the strain-induced phase change is discussed.