In August 2004, the US Food and Drug Administration approved a poly-L-lactic acid (PLLA)-based injectable medical device for restoration and/or correction of the signs of facial fat loss (lipoatrophy) in people with human immunodeficiency virus. As a result, the properties of the PLLA microparticles have received considerable interest from the medical community. Polylactides have a long-standing history of safe use in medical applications, such as pins, plates, screws, intra-bone and soft-tissue implants, and as vectors for sustained release of bioactive compounds. The L-isomer of polylactic acid is a biodegradable, biocompatible, biologically inert, synthetic polymer. Putatively, PLLA microparticles initiate neocollagenesis as a result of a normal foreign-body reaction to their presence. The build-up of collagen over time creates volume at the site of injection, while the PLLA microparticles are metabolized to carbon dioxide and water and expelled through the respiratory system.