The present Festschrift is dedicated to the human cytogeneticist Máximo E. Drets on the occasion of his 80th birthday. Máximo E. Drets will be most remembered by his peers for his seminal paper published with Margery Shaw in Proceedings of the National Academy of Sciences of the United States of America describing the G-band technique of human chromosomes. Nevertheless, his role as a key person in Latin American science development transcends single achievements. This volume provides a collection of twenty original and review articles contributed by Máximo's former coworkers and colleagues of the Americas and Europe who over the years have shared with him common research interests in the fields of chromosome biology, cytogenetics, genetic damage and evolution.