The pair poly (vinyl alcohol) (PVAI) and poly (vinyl pyrrolidone) (PVP) was shown to form completely miscible blends based on following experimental results. A single glass transition temperature was observed by DSC and optically clear films were obtained by casting solutions with DMSO as common solvent. Long spacings of PVAI increased with increasing of the content of PVP rapidly and thickness of lamellae of PVAI was changed slightly as derived from SAXS- It could be explained that two amorphous phases of PVAl and PVP were miscible nad sandwich among lamellae of PVAl. Comparing with plain PVAl and PVP infra-red absorption bands of hydroxyl group (OH) of PVAl and carbonyl group (CO) of PVP in blends shifted towards low vibrating frequency. It suggested that hydrogen bonds were formed between PVAl and PVP. Flory-Huggins interaction parameters calculated based on equili-brium melting points was -0.88.