Pressure drop of monofilament-woven fabrics is often calculated via the so-called orifice model in which a discharge coefficient is assigned to the weave's unit cell. In all previous models of woven fabrics, the filaments were assumed to have circular cross-sections-an assumption which is not entirely accurate especially when there is a considerable tension in the warps and wefts. Following the methodology developed by Lu et al. [1996. Fluid flow through basic weaves of monofilament filter cloth. Textile Research Journal 66 (5), 311-323], a new set of expressions are derived for calculating the most constricted open area, and so the discharge coefficient, of plain-woven monofilament fabrics having filaments with elliptical cross-sections. Conducting numerical simulations for computing the pressure drop of such fabrics, we observed a logarithmic relationship between the discharge coefficient and the Reynolds number. It was also shown that the discharge coefficient decreases by increasing the aspect ratio of the filaments' cross-section. (c) 2007 Elsevier Ltd. All rights reserved.