Solid lipid particles have been introduced since the early 1990s as an alternative drug carrier system to emulsions, liposomes and polymeric microparticles. This review presents an overview of the advantages and drawbacks of lipid particles, focusing on lipid microparticles (LMs), i.e. particles with dimensions in the micrometer range. Specific focus is on the role of the main excipients used for LMs formulations, lipids and surfactants, and their effect on LM properties. Furthermore, an update on preparation techniques and characterization methods are also presented. The interaction of LMs with biological systems will be also reviewed together with administration routes,with particular attention to most recent applications.