Abstract: The electrophoretic patterns of LDH isoenzyme smserum,cardiac musck,liver,kiderny,skeletal muscle and gonad were studied in male and female Monopterus albus by means of polyacrylamide gel disc electrophoresis.The results indicated that the LDHisoenzyme patterns of Monopterus albus exhibited tissuer-speeificity.There wereintersexual differences in some LDH isoenzyme patterns in the same tissue,suggestingthat the factor controlling the expression of LDH isoenzyme in Monopterus albus wasdifferent between sexes.