National audienceThe 12th international conference on the health effects of incorporated radionuclides, HEIR 2018, was organized jointly by IRSN and CEA and took place in Fontenay-aux-Roses, from October 8 to October 11, 2018. This international conference gathered more than 140 scientists from all over the world and discussed all the aspects of internal contamination with radionuclides, namely biokinetics and dose assessment, epidemiology, biological and health effects, treatments and decorporation. For the first time in this cycle of conferences, a session was dedicated to the medical use of radioisotopes and to the questions arising with this medical use. This paper presents an overview of the main results presented during this meeting. ...