Poly(ether urethane) (PEU)-Nylon 6 block copolymer film prepared via melt pressing and subsequent quenching in liquid nitrogen exhibited a one-phase structure due to the specific interaction between urethane groups in the PEU block and the amide groups in Nylon 6 block through hydrogen bonding. Contrary to this, the solvent cast film showed a microphase separated structure which had risen from the poor solubility characteristics of the PEU block in the solvent. However, by heat treatment, the mutual miscibility of the block copolymer increased as a result of the hydrogen bonding formation. The block copolymer and Nylon 6 binary blend showed that these two polymers are compatible over the entire composition range mainly due to the specific interactions between the urethane and the amide groups in the blend through hydrogen bonding. The block copolymer in the ternary blend which consists of polyurethane (PU), Nylon 6, and the block copolymer prepared by melt extrusion was soluble in either of the PU and Nylon 6 homopolymers, inducing a homogenizing effect.