Up till now, in the French Polynesia and in New Caledonia, people showing ciguatera intoxication receive a standard treatment: calcium + vitamins B6 and C by intravenous way and in addition, some drugs arriving to cure some symptomatic manifestations. In 1988, an investigation carried out in Majuro, Marshall Islands concluded that intravenous mannitol is efficient in the treatment of serious intoxications with suspecting cerebral oedema. Since, such a treatment has been utilized with success in several endemic areas. Our therapeutic evaluation was arrived to determine whether mannitol's efficiency is higher than the standard treatment in the ciguatera intoxications of mean seriousness. This investigation was carried out on two randomized groups: The first one receiving mannitol (250 cc intravenous at 20% injected in 1 h) the second one receiving the standard treatment (intravenous perfusion glucose serum 250 cc with 1 g of vitamins C, 250 mg of vitamin B6 and 1 g of calcium gluconate injected in 1 h). Seriousness of clinical status was evaluated according to a scale of score from 0 to 50, based on the importance of the clinical manifestations paresthesia, aches, asthenia, cardiovascular and digestive signs. Only patients getting a score at least 20 were included in this investigation. Clinical status of each patient was evaluated before any treatment (initial score) at the end of perfusion and at the 24th hour. Efficiency of each treatment respectively was evaluated according to the differences between these three different scores. CHI 2 and U Mann's and Whitney's tests were utilized for the statistical analysis.(ABSTRACT TRUNCATED AT 250 WORDS)