We present the first case of small cell lung cancer with Lambert-Eaton myasthenic syndrome during hemodialysis (HD). A 72-year-old male patient receiving HD experienced progressive muscle weakness. He was diagnosed with small cell lung cancer with Lambert-Eaton myasthenic syndrome due to an increased serum level of anti-voltage-gated calcium channel antibody and aspiration cytology on endobronchial ultrasonography for the swelling of a subcarinal lymph node. He received chemotherapy consisting of carboplatin (300 mg/m(2)) and etoposide (50 mg/m(2)), to which he had a partial response. However, the second therapy course could not be administered because of the unexpected development of severe hematological adverse events, which also prevented him from undergoing further HD. This case indicates that caution should be taken when using chemotherapy for such patients because of hypotension due to chemotherapy, with which it is impossible to undergo HD.