Quantitative electromyography (EMG) usage in daily clinical medicine can exclude the investigation results influencing by the electromyographer's subjective factor in needle EMG. The aim of our study was to compare the diagnostic efficiency of these quantitative EMG methods which have found some more consistent application in routine neurologic practice. We have investigated 35 healthy subjects and 59 patients with two basic types of neuromuscular disorders (neuropathies and myopathies) by means of four quantitative EMG methods: 1--modified Buchthal's low threshold MUAPs (motor unit action potentials) analysis; 2--interference EMG pattern Dorfman's and McGill's limited decomposition; 3--interference EMG pattern spectral analysis; 4--interference EMG pattern turns-amplitude analysis. In results analysis parameter's 95% confidence intervals were calculated by Campbell and Gardner and the difference between three subject groups (controls, neuropathies, myopathies) was evaluated by special multidimensional statistics (Hotelling T2 test) using simultaneously all tested parameters of four quantitative EMG methods. The modified Buchthal's low threshold MUAPs analysis was the most effective method in discovering neuropathy and myopathy with area as the best discriminating parameter. The diagnostic power in neuropathies may be increased using selected quantitative EMG methods or theirs individual parameters combinations. Several aspects of applyied quantitative EMG methods and aquired data statistical analysis are discussed.