1. To discover whether bees learn the colours of landmarks, individually marked foragers were trained to collect sucrose from a small reservoir on the floor of a room. The reservoir was placed at one of two sites each defined by its position relative to one of two different arrays of cylindrical landmarks. On each foraging trip, a bee encountered one of the two arrays. Once a bee was trained to both arrays, its pattern of search was occasionally recorded on videotape during test trials in which one array of landmarks was present and the sucrose absent. 2. Both training arrays were composed of two dark blue and two light yellow landmarks placed at the corners of a square. The arrays differed only in the arrangement of coloured landmarks. When bees were tested separately with each array, they searched close to the reward-site defined by that array (Figs. 1 and 2). They behaved similarly on tests in which dark yellow and light blue landmarks replaced the dark blue and light yellow landmarks respectively (Fig. 3). To distinguish between the two arrays, the bees must have used the arrangement of colours.