Introduction Lumbosacral plexus consists of ventral branches of roots L1-S4 and is divided in two relatively separate portions. The lumbar plexus originates in L1, L2, L3 and part of L4 and frequently receives contribution from Th12. The sacral plexus consists of lower branch L4 and ventral branches L5-S4. EMG examination of lumbal and sacral plexopathies often yields suboptimal results. Electrodiagnosis of lumbal plexopathy relies on needle EMG. Routine motor and sensory nerve conductions studies are unavailable for most of its terminal branches. For the sacral plexopathy the motor and sensory amplitudes of the peroneal, tibial, ischiadicus and suralis nerve may help by showing axonal involvement. Conversely, reduced nerve conduction velocities can point to a more diffuse demyelinating neuropathy. Aim Evaluation of the role of various neurophysiological methods in diagnostic work up in various lumbosacral plexopathies. Methods In motor nerve conduction studies not only common stimulations points but also proximal root stimulation with use of magnetic coil can be exploited. In sensory nerve conduction studies the needle stimulation or needle registration is an option. For diagnosis of plexus or root lesion F-wave studies or H-reflex (also for femoral nerve) can be used. Somatosensory evoked potentials may be important for setting the diagnosis. Not only distal – easy accessible – muscles, but also proximal and paraspinal muscles should be investigated. Results Some typical case reports are displayed with clinical findings and neuroimaging correlates (diabetic radiculo-plexopathy, autoimmune lumbosacral plexopathy, neoplastic, traumatic, ischemic and inflammatory plexopathies). Conclusion EMG has an important role in differential diagnostics of plexopathies. The use of various electrodiagnostic methods demand broad spectre of skills in EMG laboratory and deep knowledge of individual plexopathies.