Imported malaria is the most common cause of fatal infections in returning travellers. The increased amount of both tourist movement and migration has resulted in a growing number of people at risk of infection. In the present study, 507 malaria patients admitted to Italy's National Institute for Infectious Diseases in Rome between January 1984 and December 2003 were studied. Overall, 445 cases, or 87.7%, were acquired in Africa, of which 55% were acquired in five sub-Saharan countries. Plasmodium falciparum accounted for 393 (77.5%) of the imported cases. Patients consisted of short-term travellers (n = 213, 42%), long-term visitors (n = 134, 26.4%), and immigrants from endemic areas (n = 137, 27%). Malaria chemoprophylaxis was completed in less than one-quarter of all patients, with immigrants having the lowest rate of completion: only 3.6% of immigrants fully completed chemoprophylaxis compared to 31% of short-term travellers and 29.1% of long-term visitors (p < 0.001). Upon multivariate analysis, the lack of chemoprophylaxis was independently associated with the occurrence of severe malaria (p = 0.009). Severe malaria was reported in 59 (11.6%) individuals: all 11 deaths due to severe P. falciparum infection occurred in patients from sub-Saharan countries, two of whom were immigrants from countries where malaria is endemic. Malaria poses a serious health threat to individuals visiting endemic areas. Ensuring the correct chemoprophylaxis for all travellers, including immigrants from endemic areas, and providing prompt access to healthcare providers for unhealthy returning travellers are major points still to be addressed in Italy.