The characterization of the L-type PK were made of PK extracted from the liver of a patient with congenital hemolytic anemia associated with an erythrocyte PK variant, PK Nagasaki. The L-type PK of PK Nagasaki showed the following parameters: slow migration on electrophoresis, high Km for PEP without F-1,6-P2, less activation by F-1,6-P2, normal Km for ADP, high utilization of UDP, acidic pH optimum, and instability to urea and heat. These tests served to differentiate this L-type PK variant from the other variants previously reported. At the same time, both the Km for PEP with F-1,6-P2 saturation and the electrophoretic mobility of L-type PK were found to be different from those of the erythrocyte PK and PK Nagasaki. Though the liver cell, with regard to L-type PK, has only the less functional and less stable mutant L-type PK there is no evidence of liver dysfunction or damage, although there is chronic hemolytic anemia.