This is the 11th of the Pediatric Nephrology series created to help us be in touch with developments which are relevant to the problems we face daily in clinical practice and the questions we ask and try to answer in clinical and experimental research. Like volume IX, this one focuses on one of the subgroups to which we are committed--the neonates' special fluid and electrolyte requirements. This volume has more on blood pressure and renal function and looks at the hormonal regulators. There is greater depth about intoxications and nephrotic agents, congenital disorders and mineral metabolism. The exchanges were stimulating and the controversies were brought out without need of much of my usual prodding. At Julie Ingelfinger's suggestion, at the end of each panel discussion I have added a comment to highlight the main points as I see them. Otherwise, the format remains as in past editions: the papers given related to the four major topic areas, each followed by panel and registrant discussion. Although the transcription is almost verbatim, you will not find the names of the discussants, purposely omitted to ease my editorial work and to encourage everyone to speak candidly. Some of the questions and answers are those submitted to the panelists after the sessions, incorporated here by request. Also, frequent references are made to others' work but their names have been omitted.