The case of a girl carrier of the Rett syndrome is presented. During the first year of life general growth and psychomotor development were normal. Afterwards progressive neurological and mental impairment, loss of ability for the intentional use of hands together with stereotyped movements were seen. At the same time autistic behaviour, progressively abnormal EEG and microcephalia as well as bruxism were evident. Clinical diagnosis was done according to internationally accepted criteria.