It is the objective of this chapter to review the hydrophobically modified water-soluble and other hydrophilic nanostructured polymer systems and their biocompatibility for potential use in biomedical applications. The nanostructured polymer systems reviewed include block copolymers, amphilic copolymers, nanostructured polymer blends, and networks that exhibit hydrophilic/hydrophobic micro-/nanophase domain structures. Enhanced biocompatibility and mechanical strength appear to be a general characteristic of such systems as compared to single phase hydrophilic polymers. Fabrication of solid surfaces in terms of chemical affinity including hydrophilicity is a technology of importance in the development of various devices and functional materials. In particular, super-hydrophobic/super-hydrophilic patterning is crucial because it is applicable to the control of liquid flow and the immobilization of functional materials into specific areas. The ability to create superhydrophilic-superhydrophobic micro patterns and arrays on nanostructured polymer blends is essential for a variety of applications ranging from micro fluidics to cell microarrays. Despite a lot of research done on the development of new superhydrophobic and superhydrophilic surfaces on nanostructured polymer blend films, creating precise, and stable micro patterns of superhydrophilic and superhydrophobic areas has proved challenging. To the best of our knowledge, most of the existing methods are based on the surface modification of a rough superhydrophobic and or superhydrophilic substrate through a mask to reverse hydrophobicity of the exposed areas.