A new human small cell lung carcinoma (SCLC) cell line, designated MT-428, was derived from a patient who showed neurological paraneoplastic syndrome (combined with subacute cerebellar degeneration and peripheral sensory neuropathy) and was established in tissue culture. This cell line exhibited small cell (variant type) morphology as observed by phase contrast and electron microscopy. The MT-428 cells had a doubling time of 72 hours. Chromosomal analysis showed complicated rearrangements at short and long chromosomes with a modal number of 68. Several tumor markers, NSE, TPA and CPK-BB, were detected in culture medium. This cell line had a cloning efficiency of 1.3% in 0.8% methylcellulose. Finally, it should be noticed that autoantibody against MT-428 cell was demonstrated in serum of the patient. We concluded that the MT-428 cell line may provide a suitable model for studies of neurological paraneoplastic syndrome.