Résumé : During the course of Schistosoma mansoni murine infection there is a dramatic increase of some immunoglobulins and S. mansoni-specific antibodies. The most substantial response is initiated after 40 days of infection and results in a prolonged increase of total IgG1, IgM and IgA. The maximum increase is respectively 26, 14 and 3-fold the basic immunoglobulin level in control mice. Some anti-S. mansoni classes and sub-classes were studied by an original radio-immunoadsorbent test. Anti-S. mansoni IgG1 and IgM antibodies appear and increase at the same time as that of total IgG1 and IgM. Anti-S. mansoni IgA antibodies appear later (80th day) and correspond to a second peak of total IgA.