Depending on the two-dimensional structure of woven geotextiles, analytical solutions have been proposed to predict the pore size characteristics of woven slit-film geotextiles under certain uniaxial tensile strains. The strained per cent open area (POA) and equivalent pore size have been expressed as functions of tensile strain. The physical properties of woven geotextiles, such as the mass per unit area of a geotextile and the density and size of slit films, have been used in predicting the strained pore size characteristics of woven slit-film geotextiles. The influence of uniaxial tensile strain on pore size characteristics of two woven slit-film polypropylene geotextiles was evaluated by image analysis. Several pore size parameters corresponding to different strains were measured, including POA, pore size distribution (PSD), and O-95. A comparison has been made between the analytical and experimental results, and the experimental data of previous studies have been used to confirm the validity of the analytical solution. In addition, the image analysis results show that the POA and O-95 increase with the uniaxial tensile strain. The PSDs move towards the direction of the large open sizes with increasing levels of stain. (C) 2013 Elsevier Ltd. All rights reserved.