Both paper and ion exchange chromatographic techniques have been used to identify and make a partial quantitative estimate of amino acids in surface water samples collected in four subtropical regions. The most abundant of the 18 amino acids identified were aspartic acid, threonine, serine, glutamic acid, alanine, valine, isoleucine, and leucine. In general, basic amino acids, possibly except for lysine, seem to be in low concentration. The amino acid composition of hydrolysates of proteinaceous material in sea water varies in the samples. These differences may be important in the ecology of marine organisms.