Abstract: The uptake of ornithine and its transformation to polyamines through ornithine decarboxylase pathway in S. japonicum were studied. The total uptake of 14C-ornithine by S. japonicum was proportional to both the concentration of 14C-ornithine and the time of incubation.The worm were homogenized in 5% TCA after cultivation and the TCA extract was reacted with DNS-C1. The radioactivity of DNS-derivatives of 14C-polyamines was determined by thin-layer-chromatography, radio-autography and liquid scintillatic measurement. It was shown that an obvious amount of 14C-putrescine and a limited amount of 14C-spermidine were formed. In case the homogenate of S. japonicum was incubated with 5-14C-ornithine in pH 8.0 Tris buffer or in pH 7.2 phosphate buffer system in the presence of pyridoxal, the production of 14C-putrescine and 14C-spermidine was found to be 2, 000 cpm and 300 cpm per 40 ♀/4 hours respectively.When proline-DNS derivative was assayed by two dimensional chromatography on polyamide membrane after 8 hours cultivation, 1,000 cpm of 14C-proline would be found in 120 worm pairs.