Bilayer Sustained release tablets are widely used for sustained release drug delivery system. Sustained release tablets enhance patient compliance by minimizing dose frequency and increase stability by protecting the active ingredient from hydrolysis and degradation. It releases drugs at fixed and expected rate in a controlled manner either by dissolution or diffusion control mechanism. The active content is uniformly dispersed in the rate controlling agent i.e. polymers, which may be hydrophilic, plastic, lipid, or mineral. The polymer acts as release rate retardants. Hence it controls drug blood level with uniform therapeutic level and avoid fluctuation thus prevent local or systemic adverse reactions. The various approaches for matrix tablet preparation, polymers, factors and evaluating methods are discussed in this review.