The complement system is an often-overlooked part of the immune system, responsible for various rare diseases. Two examples for these diseases are atypical hemolytic uremic syndrome (aHUS - a nephrological illness) and paroxysmal nocturnal hemoglobinuria (PNH - a hematological illness). aHUS is caused by genetic alterations in genes coding for complement regulation, PNH is caused by an acquired mutation in bone marrow cells, causing red blood cells triggering complement activation. aHUS can result thrombotic events in the kidney, as well as other organs and, when left untreated end-stage renal disease requiring transplantation. PNH results in life-threatening hemolysis and thrombosis when left untreated.  Since approximately 10 years these diseases can be treated with therapeutic complement inhibitors. However, these drugs are expensive (>400.000 euro per person per year) and frequently not dosed optimally. Model-informed precision dosing can then help to simultaneously improve treatment and reduce costs.  This presentation will focus on the development and implementation of model-informed precision dosing for complement inhibitors in collaboration with patients, healthcare professionals, government, and healthcare insurers to enable sustainable and personalized treatment.