Forty one (69%) were Portuguese emigrants working in Africa (for a period of two or more years in 20 patients and varying from two to 34 years; for a period of up to two years in14 patients and for a period that has not been defined in 7); seven patients were tourists and other seven lived in Africa and came to Portugal (five were Africans that came to visit friends and relatives and two were immigrants), and four worked in boats that had made several stops in seaports along the way. All but three had returned from sub-Saharan Africa: 48 (81.3%) from former Portuguese colonies in Africa -Angola (31), Mozambique (9), Guinea-Bissau (7) and Sao Tome and Principe (1); the others had returned from Senegal (2) and Gabon, Malawi, Burkina Faso, Central African Republic, Nigeria, and Côte d'Ivoire, one patient from each country; two other patients had returned from Thailand and one from the Philippines. Fifty one patients (86.4%) were white, six black and two Asian. Malaria immune status was evaluated in 54 (91.5%) patients: 25 (46.3%) were nonimmune and 29 (53.7%) semi-immune, according to the defined criteria. Chemoprophylaxis was prescribed to 14 (23.7%) patients, but discontinued or not taken properly, except from one patient with cerebral malaria that was on mefloquine chemoprophylaxis.