SLN constitute an attractive colloidal drug carrier system due to successful incorporation of active compounds and their related benefits. Their benefits are still being demonstrated and new approaches are introduced. SLN offer an economical and patient-friendly device for administration of drugs by various routes. Coating of SLN with hydrophilic substances is very promising in the treatment of various diseases such as cancer and tuberculosis. Reports on surface modification of SLN by PEG coating have distinctly increased attention of various research groups with the aim of improving drug bioavailability. The concept of surface modification is further increasing the importance of SLN among traditional colloidal drug carrier systems.