Ugo Amaldi has worked at CERN for thirty-five years, participating in and leading numerous experiments in particle physics and giving, in particular, significant contributions to the study of weak interactions and the unification of the fundamental forces. For thirteen years he has been spokesperson of DELPHI - one of CERN's international collaborations at the accelerator LEP, predecessor of LHC. Already in the 1950s he developed an interest in medical physics; in 1992 he came back to this subject with the creation of the TERA Foundation, which promotes research in oncological hadron therapy. In 2011, as a result of Amaldi's initiative, the Italian National Hadrontherapy Center for Cancer Treatment CNAO was opened in Pavia. In the last thirty years more than one third of the Italian high-school pupils have studied physics on his textbooks.