Perspectives and DilemmasDevotees of Bacchus notwithstanding, water has been a major determinant of the life and death of men and civilizations. That it also is the anlage of our earliest phylogenetic and ontogenetic habitat has probably contributed to the intense interest in, and study of, the metabolism of this ubiguitous compound. Since body water is of such importance to the survival of the organism, one anticipates, at least on teleological grounds, the existence of homeostatic mechanisms for the maintenance of its integrity. The purpose of this paper is to review briefly current information and concepts about these mechanisms, including the neurohypophyseal antidiuretic hormone (ADH) and other possible antidiuretic mechanisms, with special reference to their role in disturbances of water metabolism.In particular, one question concerns us: Does increased ADH activity play an important causative role in water-retaining states like hepatic cirrhosis, congestive heart failure, and the nephrotic syndrome? The relevant experimental data may be grouped as follows:1. Evidence pertaining to the role of the neurohypophyseal ADH in water-retaining states. 2. Evidence that increased ADH activity may not play a role in water-retaining states.3. Further evidence for extrahypophyseal antidiuretic mechanisms. hepatic cirrhosis 2 or from congestive heart failure 3 has suggested increased ADH