Incoordination is frequently observed in patients following a cerebrovascular accident. Clinical electromyographic studies which have furthered our understanding of this motor impairment are reviewed, and possible underlying mechanisms are discussed. It is suggested that the lack of coordinated voluntary movement observed in hemiparetic patients may be due, in part, to an impaired regulation of spinal neurones. In the rehabilitation sciences, the need to assess the effectiveness of treatment as well as develop new approaches for the treatment of hemiparetic subjects will require the combined efforts of many investigators. A two-fold research approach is supported which aims: 1) to quantify the motor deficit, and 2) to extend our knowledge of the physiological mechanisms underlying the deficit. Such a general research approach could be of value to the study of other sensorimotor deficits.