This vol.Dle of Advances in Experinental ~dicine and Biology is based on an Arrerican Chemical Society SympositUII entitled: "Surface Chemistry of Biological Systems", which took place in New York on September 11-12, 1969. Thanks to the special photo offset process used by the publishers, the papers are appearing very soon after their presentation, and at a lower cost than usual. These advantages are appreciated by the scientific community. As the title of the vol.Dle indicates we have attempted to bring the scientific approach and techniques of surface chemistry to the complex problems of biological systems. Two previous sym­ posia in this field have been published, one in the Journal of Colloid and Interface Science (24:1-127, 1967) and the other in the Journal of General Physiology (52:187S-252S, 1968). The previous publication outlets, a chemical and a biological journal, help to emphasize the interdisciplinary nature of the material and also the appropriateness of the choice of Advances in Experinental Medicine and Biology for the C1.lr'rent symposium.