We have created a method for measuring the orientation of cilia in the respiratory epithelium. Ciliary orientation is the direction perpendicular to the plane defined by the central tubules of the cilia and is an estimate of ciliary beat direction. Ciliary orientation can be estimated by measuring the angle between the plane defined by the central tubules and a reference line. The standard deviation of these measurements describes the variation present in the beat directions of the cilia. The reference line must be so chosen that the majority of measurements falls at about the middle of the 0 degree-180 degrees range. We tested measurements by using both a glass angle measure and a semiautomatic image analyzer (IBAS I). The latter approach was faster and more reproducible. We made our measurements of normal tissues on samples obtained from two healthy adult non-smokers. Measurements were made in four areas of each sample, with 59-110 cilia in each. The differences between the maximum and minimum angles of the ciliary orientation in the same area varied from 167.9 degrees to 85.4 degrees from the reference line. The standard deviation varied from 18.0 degrees to 35.4 degrees and we consider this to be a normal variation in ciliary orientation. Of the cilia, 57% were within a standard deviation of 20 degrees.