Miscibility in the crystal phase was investigated for blends between two types of poly(vinyl alcohol)s (PVAs) with different syndiotacticities, 54 and 58 mol% of diad content. They were basically in isomorphic relation with each other, and were designated as atactic (a-) PVA and syndiotacticity-rich (s-) PVA, respectively. The melting temperature measured by differential scanning calorimetry and the crystal dispersion temperature obtained by thermomechanical measurements were used to describe the phase structure of the blends. A cocrystallized phase was found with miscible amorphous phase. Phase separation into a-PVA-rich and s-PVA-rich crystal phases was found locally at blend compositions with small contents of s-PVA. Analysis of these coexisting crystal phases by using a drawing and relaxing method was shown to be useful for discussion of the two structures in terms of the excess free energy of each crystal phase.