A new system for computer aided EMG-analysis was tested in 3 groups of patients with neurogenic lesions (ALS, ulnar nerve lesions, diabetic polyneuropathy). The system entails automatic segmentation and parametrization of the single MUAP as well as the automatic classification of the MUAP into motor units. Emphasis was placed on its practicability in an everyday clinical setting. All patient groups differed significantly from normal groups in most of the computed parameters of the motor units. Moreover, on the basis of the computer-aided analysis of the MUAP up to 90% of individual patients in the ALS and ulnar nerve lesion groups and up to 40% in the diabetic polyneuropathy group, who did not have any pathological spontaneous activity or paris, could be classified as pathological. It is concluded, that computer-aided EMG-analysis has become a practical tool for routine use in the clinical laboratory simplifying early diagnosis of subtle EMG-changes, and aiding the less experienced examiner.