A semi-empirical model has been developed to optimize the design of pleated filter panels used in cabin air filtration. The study was performed for clean, ventilation-type filters with the triangular pleat configuration. The objective was to optimize the pleating design to provide minimum pressure drop at design flow rates. The parameters investigated included the pleat count, pleat height, approaching velocity and filter media type. Two different filter media (3M 0104 and 0105) at two different pleat heights (2.70 and 3.60 cm) were studied. The approaching velocity was varied from 1.65 to 5.84 m/sec by a combination of three different cross sections (161, 226 and 355 cm2) and three different flow rates (3540, 4248 and 5663 lpm). For each combination of pleat height, approaching velocity and filter media, a curve giving pressure drop vs. pleat count per unit length was obtained.