Introduction Decurrent of pathologies of the central nervous system, the spasticity generates deficit in the motor and postural control, pain and alterations in the reciprocal inhibition; it constitutes an important incapacitant factor for the execution of activities of daily life, therefore the interest in the correct evalu- ation of this implication. There are two methods for its measure: subjective or objective. The first one involves scales and questionnaires as the question- naire of auto-measure and the modified Ashworth Scale (mAS), what is the most used method, because of its practicity. The objective methods are those that given quantitative data of the patient spasticity and that being independent of professional experi- ence, excluding this subjectivity. In relation to these methods the biomechanic pointers proceeding from the analysis of kinetic, kinematic and electromyog- raphy (EMG) parameters are distinguished. In relation to EMG parameters, they are meth- ods used mainly to quantify the spasticity in a mus- cle through direct EMG register. However, it is known that the spasticity modifies a reflected mech- anism of motor control called of reciprocal inhibi- tion. Few are the studies directed to evaluate the muscular spasticity through the degree of recipro- cal inhibition that the patient presents. Procedure that can be executed, basically, through the analysis of the relation in the standard of agonist and antag- onist muscular activation during the execution of one determined gesture. It is believed that from this relation and of the adjusted processing of EMG Electromyogr. clin. Neurophysiol., 2008, 48, 000-000. 1 1 Post-Graduation Program Interunits in Bioengineering – São Carlos Engineering School – São Paulo University. 2 Human Movement Applied Physiotherapy Laboratory of the Science and Technology College – São Paulo State University. Comparative analysis of electromyographic pattern in the forearm muscles of hemiplegic patients H. U. Kuriki 1,2 , F. Mícolis de Azevedo 2 , R. de Faria Negrão Filho 2 , N. Alves 2 , A. Cesinando de Carvalho 2 Abstract It was purposed the use of electromyography (EMG) to evaluate the activation of the agonists and antago- nists muscles of spastic patients, to test the viability in the development of an instrument that given quantitative data of the patient spasticity. 30 hemiplegic and 15 normal volunteers had been submitted to the EMG of flexor and extensor carpi ulnaris muscles during the flexion and extension movements of the wrist. The individuals with less severe spasticity (mAS (modified Ashworth Scale) ringing 0 to 3 degree), had presented deficit in the activation of the flexor muscles in plegic side in relation to the non plegic side and that the individuals seriously compromised by the spasticity (mAS =4 degree) present deficit of reciprocal inhibition. One evidenced is that the non plegic member does not present a similar neuro-motor comportment when compared to the normal mem- ber.The surface electromyography is a practical clinical instrument to evaluate the patient with spasticity and the hemiplegic patient needs to be evaluated on both sides (deficient and no deficient) because the no compro- mised side do not show a normality standard. Key-words: Hemiplegia – Spasticity – Agonist-antagonist relationship – Surface electromyography.