The literature lists a number of methods of EMG examination which afford information on supranuclear motor disturbances. A number of these tests were selected for further evaluation. These tests yielded 24 EMG variables. Three groups of test subjects were studied: 39 normal test subjects, 27 patients with spastic syndrome and 23 patients with a Parkinson syndrome. Efforts were made to establish which EMG tests can contribute to differentiation of these three categories. The following test battery yielded sufficient relevant information: (a) testing the KJR, ATR and HR, using skin electrodes; (b) testing an agonist and antagonist at relaxation and slow passive stretching, using needle electrodes; (c) if necessary, supplementary testing of the vibration reflex. Spastic patients show an increased KJR with Jendrassik (m 4.6 mV), A/M quotient (m 0.31), H/M quotient (m 0.50), and usually a positive stretch reflex; the vibration reflex is diminished (m 8.2°). Parkinson patients show no electrical silence at relaxation but spontaneous action potentials, irregular groups of action potentials and/or tremor (frequency m 4.6/sec), and usually a positive stretch reflex