Nine cases of acute arthritis in hemiplegics are reported, which appeared in the early convalescent stage of cerebrovascular accident cases, exclusively or predominantly in the paralysed limbs. The arthritis was preceded by infections of the respiratory, urinary or biliary tracts. The arthritis healed without sequelae in a few weeks and no recurrences were observed. It is assumed, that the predominant localisation of the hyperergic synovial reaction may be explained by the increased susceptibility of the vegetative nervous system on the hemiplegic side, induced by the cerebro-vascular accident.