Abnormal electrophoretic pattern of serum lactate dehydrogenase isoenzyme is shown. In this case electrophoretic pattern showed a sharp single band between lactate dehydrogenase 4 and lactate dehydrogenase 5 and broad band between lactate dehydrogenase 2 and lactate dehydrogenase 4. This abnormality was suggested to be caused by the presence of lactate dehydrogenase and immunoglobulin G (kappa type) complex at least in part. There were no abnormalities of other laboratory data in this case.