The complexation behavior between poly (2- hydroxypropyl methacrylate) (PHPMA) and three isomeric tertiary amide polymers, namely, poly(N-methyl-N-vinylacetamide) (PMVAc), poly(NN-dimethylacrylamide) (PDMA), and poly(2-ethyl-2-oxazoline) (PEOx), was studied. PHPMA forms interpolymer complexes with the three tertiary amide polymers at the entire feed composition range in methyl ethyl ketone and tetrahydrofuran solutions, indicating a strong intermolecular interaction between different polymer chains. However, complexation does not occur between PHPMA and the three tertiary amide polymers in NN-dimethylformamide solutions. Infrared spectroscopic studies show that the intermolecular hydrogen bonding association between the hydroxyl groups in PHPMA and the amide carbonyl groups in the tertiary amide polymers is stronger than the self-association between the hydroxyl groups and the ester carbonyl groups in PHPMA. PHPMA has a stronger complexation ability with these tertiary amide polymers than poly (styrene-co-allyl alcohol) and poly(hydroxyether of bisphenol-A) do.