In Marseilles, 250 medical practitioners have been questioned about imported malaria cases observed in their medical practice. In 1978, they confirmed parasitologically 18 malaria cases of which only 2 cases were admitted to an hospital; in 44 other suspected cases, the diagnosis was probable from epidemiological, clinical, immunological and therapeutical arguments. Considering the number of medical practitioners in the city and the number of confirmed hospital cases of imported malaria during the same year, more cases have been treated outside the city hospitals. Between 1973 and 1978, 164 confirmed hospital cases of imported malaria occurred in Marseilles. The collected epidemiological data indicate the recent increase of the annual incidence and an equal number of cases in immigrants and in people returning from the topics. Among them, tourists, servicemen and merchant seamen are the groups most at risk. A high proportion of infections are with P. falciparum (67 p. 100), mainly from Africa, Malagasy and Comores. The diagnosis is only confirmed on an average of 5 days after the first medical advice and 2 patients died from P. falciparum infections. Travellers to tropical countries are often careless about taking prophylactic drugs.