Efficacy monitoring of immunotherapy (IT) is performed to adjust the therapy according to the patient's reactions, to collect data for scientific studies and to evaluate the efficacy of IT. A decrease of allergy symptoms and of drug use are the main parameters. For this, allergy diaries are most suitable. Pollen exposition should be monitored with Burkhard traps. Wheal and flare reactions in skin tests can be measured by visual inspection with quantification of the diameter on transparent foils or by means of laser scanners. Nasal provocation testing leads to subjective and objective (rhinomanometry, acoustic rhinometry) results. A change in the threshold concentration of allergen, which is needed to provoke a positive test reaction, can be used to evaluate the success of an IT. Additionally, systemic or local side-effects should be carefully revealed. Cytologic measures can be achieved by nasal lavages. Cotton samplers, cytology brushes and suction techniques are used to collect cells and nasal secretions. Early and late allergic reactions can be evaluated. Specific cell activation markers like ECP or tryptase are useful parameters in nasal secretions. T-lymphocyte subpopulations and T-cell-lymphokine-profiles can be detected. During IT, a change from a dominating TH2-cytokine-profile to a dominating TH1-cytokine-profile can be seen. For the reason of their expense, those methods are restricted to scientific investigations and only rarely used for routine diagnostics.