28 patients suffering from multiple sclerosis were treated by acupuncture. The age of the patients ranged from 24 to 60 yr. Results of the treatment were satisfactory, but remarkable spontaneous remissions, characteristic for this illness, make any treatment difficult to evaluate. In this article the peculiar behaviour of all treated patients is described: increased sensibility of the skin over the acupuncture loci, while insertion of the acupuncture needles provoke spasms, clonus and even tonic-clonic contractions of the muscles of the extremities. This phenomenon is very specific and can be used as an early sign of this ill-fated illness.