Five years after his premature death on 26 June 2002, we would like to remember Dr Giuseppe Bigi, associate professor of Clinical Immunology at the University of Milan (Italy). Giuseppe, a brilliant physician, scientist and enthusiastic experimentalist was one of the very first researchers to hypothesize the existence of stem cells in peripheral blood in the early 1980s. Twenty years ago, in an open forum in Leukemia, he proffered his hypothesis of ‘stem cell’ activity in human peripheral blood (Leukemia 1: 623–626, 1987). In the last two decades, we have witnessed an incredible advance in the field and an impact in the clinical setting. This proves how important it was, and still is, that journals continue to provide an open forum for scientists to present and debate even the most controversial hypotheses.