Improvement of solubility as well as bioavailability of drug is our main motto for this purpose solid lipid nanoparticles (SLNs) are the new approach in drug delivery system. Since a decade, several research works are performed to utilize solid lipid nanoparticles as alternative drug delivery system to colloidal drug delivery systems such as lipid emulsions, liposomes and polymeric nanoparticles. SLNs offer great promise to controlled drug delivery and site specific and gene delivery. Nanostructures lipid carrier, lipid drug conjugates, polymer lipid hybrid nanoparticles are the new emerging drug delivery system. This review concentrated on drugincorporation models, advancement in lipid nanoparticles, method of preparation, secondary production steps, characterization, application and future of SLNs. This review presents a broad treatment of solid lipid nanoparticles discussing their advantages, limitations.