The miscibility of Nylon-6 with ethylene-vinyl alcohol copolymers of various vinyl alcohol content was studied from thermal properties, Molau test, and scanning electron microscopy. Nylon-6 has a good miscibility with ethylene-vinyl alcohol copolymers composed of 43,62,71 mol% vinyl alcohol, and the blends have a single sharp glass transition temperature. But the miscibility is reduced as the vinyl alcohol content is increased or decreased from above mol%, and the blends have two sep3.rate glass transition temperatures which moved a little toward each other. As the amount of Nylon-6 in the blend is reduced, the intermolecular hydrogen bond strength of Nylon-6 is reduced, and the decrease of the glass transition temperature of the miscible blends is caused by this decreased hydrogen bond strength. The depression of melting point is observed for each polymer in the blend, and the degree of depression is increased with the improvement of miscibility. The difference in miscibility was confirmed again from Molau test and scanning electron microscopy.