An increasing number of cases of malaria, imported to Denmark, are caused by Plasmodium falciparum and severe and complicated cases are more often seen. In the Department of Infectious Diseases, Rigshospitalet, 23 out of 32 cases, hospitalized from 1.1-30.6.1988, i.e. 72%, were caused by P. falciparum; of these, seven (30%) were complicated, according to the definition by WHO. The importance of prompt diagnosis and treatment with intravenous quinine is stressed, and more recent supporting therapies including blood exchange transfusion are reviewed.