For the success of an immunotherapy regimen, adherence is a major success factor. The goal of our study was to identify the factors that positively and negatively influence patient compliance, and to create strategies to improve it. Four questionnaires were designed for different patient groups: A - after immunotherapy; B - during immunotherapy; C - before immunotherapy; D - no experience with immunotherapy. From March to October 2008, 790 questionnaires were collected. For the first group, questionnaire A was answered by 272 patients. Of these, 15.8% had dropped out of immunotherapy. Women had higher dropout rates than men (16.8% vs. 12.3%). The following aspects of immunotherapy were viewed by the patients as negative: time consuming (69.5%), adverse reactions (62.5%), insufficient patient information (53.7%), no change in use of symptomatic medication (33.8%) and no change in symptoms (60.7%). Despite the mentioned drawbacks, 74% of all patients would still recommend allergen immunotherapy. Questionnaire B was completed by 281 patients. In this group, 8.7% had already considered dropping out. The following unfavourable aspects were identified: time consuming (66.2%), adverse reactions (61.9%), insufficient patient information (54.8%), no change in symptoms (51.2%) and use of symptomatic medication (47.0%). Despite this, up to 95.4% of all patients would recommend immunotherapy. Questionnaire C was filled-out by 55 patients. The following reasons were rated by the patients as "important" or "very important" for the decision to start hyposensitization: long-lasting symptom alleviation (100%), few adverse reactions (98.2%), comprehensive patient information (96.3%), easy integration into daily routine (89.1%), re-assessment of therapy by doctor (83.3%) and reduced need for symptomatic medication (81.8%). Questionnaire D was filled in by 182 participants. 89% had already heard the term hyposensitization before. Their general knowledge regarding this therapy was average (3.23 on a scale of 1 - 6; where 1 = optimum). Long-lasting symptom alleviation (99.5%), comprehensive patient information (97.8%), easy integration into daily routine (96.1%), reduced symptomatic medication use (92.6%) and re-assessment by doctor (88.8%) were considered "very important" or "important" characters in the desired immunotherapy regime. Adherence to the hyposensitization schedule is essential for its success. The treating doctor should aim at choosing the right therapy and working out an individualized patient treatment plan. Equally important is providing information to the patient throughout the duration of the treatment. The doctor should assist the patient to create an optimized time schedule to help make the therapy less time-consuming.