Lysophosphatidic acid (LPA) is a bioactive phospholipid controlling numerous cellular responses through the activation of specific G-protein coupled transmembrane receptors. LPA is present in several biological fluids and can be secreted by several cell types. Whereas, multiple pathways of synthesis and degradation of LPA have been described, their relative contribution in extracellular secretion and biodisponibility is still a matter of debate. The first part of the present review is devoted to the description of the different enzymes involved in LPA synthesis and degradation (lysophospholipases, lipid-phosphatases), as well as to the molecules involved in LPA transport. In a second part, the different physio-pathological situations associated with LPA production, as well as the potential role played by LPA in genesis of certain diseases (cancer, obesity, arteriosclerosis) are listed and analyzed.