Abstract: The proteins of cysticercus cyst fluid and cysticercus were fractionated into 2 and 4 fractions respectively by ammonium sulfate precipitation. ELISA tests were performed by using these 8 preparations (2 crude preparations and their 6 fractions) as antigens tc determine the presence of corresponding antibodies in the sera of proved cases of cysticercosis and other parasitoses, as well as normal adults. Our study shows that a fraction of cysticercus cyst fluid, P1, has the highest positive rates in the diagnosis of cysticercosis and OD ratios of cysticercosis patients to normal persons among 8 preparations. Our study also shows that the positive rate of a fraction of crude cysticercus preparation, P25-55, is only next to P1 among 8 preparations and has highest OD ratios among crude cysticercus preparation and its fractions.With sera of hydatidosis patients, P1 is highly cross reactive, while P25-55 is less so cross-reactive. With sera of paragonimiasis patients, P1 is also cross-reactive, while P25-55 is not in 14 patients studied.In addition, there is a richer source of P25-55 than PI. Therefore, P25-55 is practically a good antigen fraction for diagnostic purpose,