Adhesion force, quartz crystal microbalance (QCM), and attenuated total reflection infrared (ATR-IR) measurements revealed that native proteins weakly adsorbed onto poly(lactide) (PLA) stereocomplexes with 3(1) helical (beta-form) crystals when compared with poly(L-lactide) (PLLA) homogeneous crystals with 103 helical (alpha-form) crystals. These observations suggest that substrate polymer polymorphs can be significant factors that determine protein-adsorptive properties.