This very excellent symposium written in Spanish was initiated from discussions at the National Congress of Pediatrics. It consists of three parts, the first deals with the physiology and metabolism of dehydration and fluid balance. The second part discusses the diagnostic problems involved, and the last part deals with the various forms of therapy. This is very fully discussed, including various solutions and their physiological actions. The charts are excellent, and there is a very complete biography. This makes excellent reading for anyone interested in the subject.