ESDU 80003 provides information for estimating the mean forces and moments on surface-mounted rectangular prisms in turbulent shear flow, typically a rectangular building in the natural wind. The prism shapes covered have cross-sections with side ratios in the range 0.25 to 4 and height/width ratios greater than 0.25. Flows with turbulence intensities up to 20 per cent are covered and data for flows for turbulence length scale/prism side up to 2 and velocity profile exponents up to 0.34 were included in the correlation. A Calculation Sheet provides a step-by-step procedure for calculating forces and moments and a worked example illustrates its use.