We conducted a clinical and electromyographical study in patients with Chagas' disease in the indeterminate or chronic stages of the illness. Altogether 841 patients were examined. Only 511 were admitted within the protocol; the remainder patients were rejected because they showed other causes able to damage the nervous system. Fifty two (10.17%) out of the 511 patients showed signs and symptoms of peripheral nervous system involvement in the form of sensory impairment and diminished tendon jerks suggesting the presence of neuropathy. Forty five of them were submitted to a conventional electromyographical examination. Fifteen of them showed normal results, while the remainder 30 disclosed a reduced interference pattern, being most of the remaining motor unit potentials fragmented or poliphasic, reduced sensory and motor conduction velocities and diminished amplitude of the sensory action potential. The findings suggest that some chagasic patients in the indeterminate or chronic stages of the disease may develop a clinical mild sensory-motor peripheral neuropathy.