Contrary to recent scepticism, systematic use of an experimental approach suggested by HAYES & HAYES (1952) shows that chimpanzees can imitate novel actions. Two chimpanzees imitated 13 and 17 novel arbitrary gestures, respectively. They were first taught to reproduce 15 gestures on the command, "Do this!", and then presented with 48 novel items. Using a rigourous coding system, two independent observers correctly identified a significant number of the chimpanzees' imitations (p < 0.0001). We conclude that after a period of tuition chimpanzees can go on to imitate arbitrary actions, providing evidence of a basic cognitive capacity for perspective-taking and cross-modal matching.