The distribution of the contents of total particulate amino acids (ΣPAA) in surface seawater of Bohai Bay, Yellow River Estuary and Changjiang (Yangtze) River Estuary were studies by R/V “Golden Star No. 2” from 1982 to 1984. Near Bohai Bay, the contents of ΣPAA in surface seawater were lower(60-80μg/L) than those of most stations outside the Bay, where ΣPAA, were> 100μg/L. Near the Yellow River Estuary region exhibited higher contents of ΣPAA, reaching 600μg/L and even at other stations outside the estuary ΣPAA contents were 100μg/L or > 100μg/L. At several stations of the inland of Changjiang (Yangtze) River the contents of ΣPAA were about 200μg/L and decreased to 186-90μg/L in the lower course of the river. But near the region of Zhoushan Island they again increased to 200μg/L. It is probable that the increase of ΣPAA contents was due to the high density of growing plankton and high contents of organic substances there.