Microfluidic systems have attracted much research attention recently in the areas of genomics, proteomics, pharmaceutics, clinical diagnostics, and analytical biochemistry, as they provide miniaturized platforms for conventional analysis techniques. The microfluidic systems allow faster and cheaper analysis using much smaller amounts of sample and reagent than conventional methods. Polymers have recently found useful applications in microfluidic systems due to the wide range of available polymeric materials and the relative ease of chemical modification. This paper discusses the fundamentals of microfluidic systems and the roles, essential properties and various forms of polymers used as solid supports in microfluidic systems, based on the recent advances in the use of polymers for microfluidic chips.