An investigation of the properties of the blends of nylon 6 (PA6) and poly(vinyl alcohol) (PVA) with varying degrees of hydrolysis was conducted. A near disappearance of the characteristics of the alpha-form PVA crystals, crystallization exotherms, and hydrogen-bonded hydroxyl groups and the tensile properties originally associated with the PVA molecules of PA6(x)PVA(y)(98) PA6(x)PVA(y)(95), and PA6(x)PVA(y)(86) specimens was observed as the PVA contents of the specimens became equal to or less than their corresponding "critical" values at 16.7 wt%, 33.3 wt%, and 50 wt%, respectively. These results support the idea that PVA molecules are miscible with PA6 molecules to some extent at the molecular level as the PVA contents of the blends become equal to or less than their corresponding critical PVA contents. In this article, we have proposed the possible reasons accounting for these properties of the PA6(x)PVA(y) series specimens with a varying degree of hydrolysis. POLYM. ENG. SCI., 49:1553-1561, 2009. (C) 2009 Society of Plastics Engineers