Virus specific IgM antibodies are very useful for the diagnosis of primer infection by the rubella and parotidis viruses. ELISA is the method usually used to detect IgM antibodies. The reactives and in some laboratories the apparatus are not always available. We carried out a serological method based on the immunocapture inhibition of hemagglutination of theses viruses by positive sera. 39 sera and 80 sera collected from patients and healthy population have been respectively studied to detect antirubella and antiparotidis IgM. The test appeared as sensitive and specific as the immunocapture IgM ELISA.