Eaton Lambert Syndrome(ELS)is a disorder of neuromuscular transmission. The defect of neuromuscular transmission is due to decrease in the release of acetylcholine guanta from nerve terminal. This syndrome is frequently associated with bronchogenic carcinoma. The diagnosis is established by electromyography, which characteristically shows 1) low amplitude of evoked compound muscle potential to a single supramaximal stimulus on nerve, 2) significant decremental response at low rates of stimulation 3) marked incremental response at high rates of stimulation. Our patient is 52year old man with dyspnea, coughing and muscle weakness of proximal lower limbs. He has small cell lung cancer and associated with ELS, Superior venacava syndrome and has metastatic lesion on right supraclavicular lymphnode confirmed by pathology. Metastatic mass and SVC syndrome are marked improved following chemotherapy and radiotherapy, however follow up EMG finding does not improved. We are here reporting one case which considered compatible for ELS, with a few elementary reviewed literatures.