19 ALS patients were submitted to motor evoked potentials (MEP) and F-wave from thenar muscles. Somatosensory evoked potentials (SEP) from median nerve were recorded as well in 16 patients. MEP were bilaterally absent in 4 patients (21%) and monolaterally absent in 6 patients (3.6%). Among patients with recordable waves, MEP and F-wave were significantly delayed. Their upper motor neuron conduction time was clearly abnormal only in one case. In SEP recordings the N9-N13 was significantly delayed, but the N13-N20 was normal. Four patients showed a combined sensory-motor dysfunction (increase of both N19-N13 interval and F-wave latency).