About 80 scientists from allover the world have gathered at the Parc Valrose Scientific Campus of Nice -Sophia Antipolis University, for the 5th UNESCO International Conference on Water and Ions in Biornolecular Systems , to present and discuss current problems in the field. The Conference proceedings comprise selected and reviewed contributions of invited plenary lectures, lectures and posters presentations which cover all the Biophysical sectors of research on the following three major topics : * Water, Ions and Nucleic Acids * Water, Ions and Membranes * Water, Ions and Proteins The organizers of the 5th UNESCO International Conference on Water and Ions in Biomolecular Systems have obtained financial support from various sponsors. They would like to express their appreciation and gratitude to these organizations for the valuable moral and financial support which has made the arrangement of these Conference in Nice possible. The Meeting has been sponsored by : * United Nations Educational Scientific and Cultural Organization * The University of Nice -Sophia Antipolis * D. R. E. T. (Defence Ministery) * Conseil General des Alpes Maritimes * Ville de Nice * The International Union of BiochernistIy * The International Union of Pure and Applied Biophysics * Banque Nationale de Paris * Air Liquide * Nice Congres The Executive Committee, Professors J. JAZ, B. PULLMAN and D.