Phosphoinostides have been known to play a role in cell signalling since the 1950s and since then, lipid signals have been discovered to play a role in many different cellular functions. Biology of Phosphoinostides is not a historical account, but a review of the current opinions of lipidsignalling research with the emphasis on the integration of the use of lipid signals in signal transduction and membrane trafficking. These two areas have traditionally been seen as separate but now anyone ignoring one area at the expense of the other does so at their peril. The regulation ofphospholipase C (and its isozymes), phospholipase D, the phosphinositide-3-kinases, chloride channel conductance by inositol (3,4,5,6) tetraphosphate, and of cytoskeletal protein activity by inositol lipids are all covered in depth. There is specific discussion of the PH and FYVE lipid bindingdomains that allow lipids to control the movement, location, and activation- state of membrane proteins. The central issue of the control of synthesis, translocation, and degradation of phosphoinositides is also given due coverage. For too long, lipids have been seen as a backwater of biology andan uninteresting topic to study. However their central role in cell function is now properly recognized and the Biology of Phosphoinositides will serve as an enjoyable and intriguing introduction to what these slippery molecules can achieve.