The Eleventh International Latin American Symposium is an important mile stone reflecting the rapid development of basic biochemistry in Latin America. The topic "Gene Expression and Its Regulation" was received enthusiastically, and, thanks to the vision of our Argentine colleagues, the program developed rapidly under the leadership of Dr. Gabriel Favelukes as General Secretary of the Symposium. It is interesting to note the tremendous progress that has been made in basic and applied sciences in Latin America over the past few years. The increasing initiative and leadership being demonstrated by our Latin American colleagues in organizing these symposia is a most satisfying development that speaks well for the future of science in Latin America. The early publication of this symposium has been made possible through the efforts of an editorial board consisting of Dr. F. T. Kenney (Oak Ridge National Laboratory), Dr. Gabriel Favelukes (University of La Plata), Dr. Barbara Ham kalo (Oak Ridge National Laboratory), and Dr. J. T. August (Albert Einstein College of Medicine). As in previous symposia, excellent support has come from the Ford Founda tion through a grant to the National Academy of Sciences, the United States Atomic Energy Commission, the National Science Foundation, OAS, and other groups. Through the cooperation of the authorities at the University of La Plata, the Albert Einstein College of Medicine (the United States cosponsoring university), and other schools, this very successful symposium was made possible.