Sea waters collected from the Pacific, the Indian Ocean and the Antarctic Sea were analyzed radiochemically. The details of the results of analysis of artificial radionuclides contained in surface water are described as follows:1. The scheme of analysis is given in Table 1, Sr90 was precipitated as carbonate with calcium and magnesium from sea water and purified by the nitric acid method. Cs137 was purified by the chloroplatinate and phosphomolybdate methods after concentration as precipitates with nickel ferrocyanide from large volume of sea water. Ce144 was analyzed by the solvent extraction, and ion exchange, method.The radioactivities of these nuclides were measured with a 4-π gas flow counter, of which back ground is about 3 cpm.2. Remarkable secular variation was found in the gross beta radioactivities of the Kuroshio waters and the peak, of which value was about 6μμc/l, was observed about one year after the nuclear explosions at the Bikini and Eniuetok atolls in 1958.The regional difference of gross beta activities between the Japan Sea and the Pacific coastal area of Japan was observed during Nov. 1961 to Mar. 1962. It may be caused by fall-out, and the activities of Japan Sea water were higher by the factor of 2 to 3 in comparison with the Pacific water.3. Secular variations of Sr90 and Cs137 contents of sea water adjacent to Japan are similar to that of gross beta radioactivity, and it was always observed that the concentrations of these nuclides in sea water were not over 1μμc/l. Therefore, Sr90 concentrations observed by the present authors show the tendency of being lower than those by MIYAKE and SARUHASHI. On the other hand, Cs137 concentrations observed by the present authors agree with those in the Pacific sur-face water reported by T. R. FOLSOM.4. Surface distributions of Sr90 and Cs137 in sea water from 1960 to 1961 were as follows:In the Antarctic Sea, their concentrations were very low, and their values ranged from 0.01 to 0.05μμc/l. In the area covering latitude of 0°to 10°N in the Pacific, their values were 0.1 to 0.2μμc/l, and 0.3 to 0.9μμc/l between 20°to 30°N and 0.3 to 0.6, μμc/l between 30°to 40°N, respectively. The maximum value was observed between 20°and 30°N.