Taken in all, we hypothesize a key role of Midkine, particularly in organ dysfunction at the basis of COVID-19 pathogenesis and also propose such protein as a potential biomarker (Table 1) of pathophysiological conditions and as a key target for new potential COVID-19 therapeutical strategies by employing anti-Midkine monoclonal antibodies to be specifically prepared for clinical use in humans. Here, MDK is linked to COVID-19.