Abstract: The free amino acids in the cystic fluid of Cysticercus cellulosae were determined quantitatively by using automatic amino acid analyzer. The cystic fluids of both subcutaneous-muscular Cysticercus cellulosae from 1.4 pigs and cerebral Cysticercus cellulosae from 10 pigs were detected. Among the 18 amino acids detected, alanine was found to be the predominant amino acid in both of the cystic fluids. The quantities of glycine and proline were higher than other amino acids in subcutaneous-muscular Cysticercus cellulosae, while threonine was higher than the rest in the cerebral Cysticercus cellulosae. A comparison was made between the quantities of amino acids in the fluids of both subcutaneous-muscular and cerebral Cysticercus cellulosae of 7 pigs by the T-test method. The results showed that the quantities of 12 out of 15 amino acids were significantly different, with particular reference to threonine, alanine, serine, and valine, suggesting that the difference in the metabolism of amino acids in Cysticercus may be related to the parasite's location in their respective hosts.