In 1918-19 the so-called spanish influenza pandemic killed about 20 to 40 millions people all over the world. In France the loss of life was reckoned between 125,000 and 250,000 civilians and 30,000 soldiers though the epidemiological data have been incomplete. The virus allegedly came from the United States of America with the American forces which landed in the western harbours of France and probably with Indochina's troops or Chinese workers hired in the French factories. The disease spread in three waves from April 1918 to February 1919. The second wave was the most severe in September, October and November. Half of the dead occured among the 20-40 old people as the older people were more disease-resistant. Lethal forms were due to respiratory complications which often killed in a few days. The government did to preventive measures that were unequally applied as the treatment could be only symptomatic. The reactions of people were astonishingly cautions probably because the papers were ordered not to deal with the epidemic as long as the war lasted for.Some new serological studies and molecular biology techniques led up to clarify the strain of the 1918 influenza virus without further understanding of its special virulence.