Transparent blend films of poly(vinyl alcohol) (PVA) and deoxyribonucleic acid (DNA) sodium salt from salmon testes were prepared by the solvent cast method from a homogeneous aqueous solution; as a new class of biopolymer-based hybrid materials. Differential scanning calorimetric (DSC), dynamic mechanical, thermogravimetric, and scanning electron microscopic analyses indicated that PVA and DNA are compatible in a wide range of compositions. As the DNA content increases, a melting peak of PVA reduces in intensity with a lower temperature shift, appearing at 203 degrees C in the PVA/DNA (50 wt%) blend by DSC. Physical properties of the blend films were evaluated by tensile strength and contact angle measurements. The tensile strength values of PVA/DNA (10 wt%) and PVA/DNA (30 wt%) blend films were 56 and 48 MPa, respectively. The surface free energy of PVA/DNA (30 wt%) blend film was 46 dyn/cm, which is identical to that of PVA, while the pure DNA film was revealed to show hydrophobicity (surface free energy 32 dyn/cm; water contact angle 104 degrees). (C) 2000 Elsevier Science Ltd. All rights reserved.