Specific immunotherapy (SIT) of hymenoptera venom allergy, in particular, has become an example for the effectiveness of the treatment of IgE-mediated allergic diseases. In vitro diagnostic procedures and the measurement of serum tryptase for risk assessment are well-established in the process of diagnose finding and therapy preparation. For monitoring and validation of the effectiveness of the SIT, however, in vitro diagnostic procedures remain controversial. Potentially useful approaches include detection of specific IgE, specific IgG4, basophile activation - represented by the CD 63 expression - and the lymphocyte proliferation and its IL10 release. Preliminary data suggest that the latter method appear appropriate, whereas the detection of basophile activation did not produce definite results.