The effect of dense sprays on particle size measurement by laser-diffraction-based techniques is examined for log-normal distributions with a wide range of Sauter mean diameters and size distribution widths. A Monte Carlo modeling technique is used to simulate scattering of light by particles, and general scattering phenomena are included by using Mie theory. By regression analysis, corrections for the SMD and size distribution width are obtained and presented in graphical and equation form. The corrections depend on the actual Sauter mean diameter and the actual width parameter of the spray and the obscuration. ration. Simulations are also performed for a limited number of Rosin-Rammler distributions, and the results for the log-normal and Rosin-Rammler distributions are compared. For log normal distributions and Rosin-Rammler distributions with n greater than 2.0, increasing the Sauter mean diameter of the size distribution increases the measurement error in SMD and decreases the error in width. Increasing the size distribution width also results in an increase in the measurement error in SMD and a decrease in the width. For Rosin-Rammler distributions with n less than 2.0, these trends are the same with one important exception: as the Sauter mean diameter increases, the measurement error in SMD decreases.