This Item@ which supersedes ESDU 01016@ provides information on pressure loss and flow characteristics in flow of Newtonian fluids through a sudden contraction of duct area. Both incompressible and compressible flows are covered and data are presented for sharp-@ chamfer- and round-edged contractions. The data may be applied also to a simple duct entry from a large space. The information is given here in graphical and equation format. The methods are also implemented in computer programs ESDUpac A0116 and VIEWpac 0116A.