The recent epidemic of cholera on the Pacific Ocean atoll of Tarawa, Gilbert Islands renewed interest in the use of coconut water as a rehydration fluid. Fifty-one samples of coconut water from Tarawa were analysed for a variety of constituents to assess its potential usefulness in the oral and parenteral rehydration of patients with cholera and other severe forms of gastroenteritis. Compared to oral rehydration fluids known to be effective in cholera, coconut water was found to have adequate potassium and glucose content, however was relatively deficient in sodium, chloride and bicarbonate. The addition of table salt to the coconut water is suggested to compensate for the sodium and chloride deficiency. In areas of the world where coconuts are plentiful, the advantages of sterility, availability and acceptability make coconut water theoretically feasible for the oral rehydration of patients with severe gastroenteritis when conventional fluids are unavailable.