The ability to carry out movements on imitation was assessed with a 24-item test in uniterally hemisphere-damaged patients. On the basis of a cutoff score derived from the performances of 100 control patients, 20% of the right brain-damaged patients were calssified as apraxic. Most right brain-damaged patients were only mildly defective, but a few showed a striking impairment. In left brain-damaged patients apraxia was not only more frequent, but also much more severe and was nearly always associated with aphasia. However, the correlation between the motor and the language disorder was not particularly high, and the link between the two symptoms was thought to be dependent on the contiguity of the underlying nervous structures.