For the purpose to clarifying the biologically active substance of B. pertussis, we prepared the filamentous hemagglutinin (FHA) from culture supernatant of the strain Tohama phase I and purified it through chromatography columns of hydroxylapatite, fetuin-Sepharose 4B and Sepharose CL 6B. There are several bands appeared in the polyacrylamide gel after SDS-PAGE, especially between 98 kD and 210 kD. The amount of 210 kD component is not proportional to hemagglutination (HA) activity of FHA among five different lots. Irons et al. reported that FHA preparation degraded the 220 kD and 210 kD polypeptides during the storage would be reduced the specific HA activity. Our result pointed out that the HA activity of purified Foffdid not relate to 210 kD component only. For the quality control of FHA purity in the B. pertussis acellular vaccine, we suggest that it would be necessary to test both HA titer and SDS-PAGE results.