Why is there more matter than antimatter in the universe? The reason might be hidden in the neutrino nature: one of the preferred theoretical models assumes that these elementary particles are identical with their own anti-particles. This in turn would lead to an extremely rare nuclear decay process, the neutrinoless double-beta decay (0nββ). The experiment GERDA now has reached a most important improvement in the search for 0nββ decay by reducing the disturbances (background) to an unprecedented low level making it the first “background-free” experiment in the field. This achievement is reported in the recent Nature article appearing April 6th, 2017 (doi:10.1038/nature21717).