The evidence of efficacy of allergen immunotherapy (AIT) for respiratory allergy has been demonstrated by a number of meta-analyses. However, the daily practice of AIT is quite different from controlled trials, facing challenges in terms of selection of patients, practical performance, and, of particular importance, use of allergen extracts of inadequate quality. We here performed a survey, named the Allergen Immunotherapy Decision Analysis (AIDA), to evaluate which criteria are used by specialists to choose a product for sublingual immunotherapy (SLIT) in patients with respiratory allergy. A questionnaire composed of 14 items to be ranked by each participant according to the importance attributed when choosing SLIT products was submitted to 444 Italian specialists. The responses of the 169 (38.1%) physicians, who answered all questions, were analysed. Most of the respondents were allergists (79%), followed by pulmonologists (10.8%), both allergists and pulmonologists (4.8%), and otorhinolaryngologists (3%); 59.8% of the respondents were males and 40.2% were females. The age distribution showed that 89.9% of the respondents were aged between 35 and 64 years. All respondents usually prescribed AIT products in their clinical practice: 31.4% used only SLIT, whereas 69.2% used both subcutaneous and sublingual administration. The rankings, expressed as means, attributed by physicians for each of the 14 items were as follows: level of evidence-based medicine (EBM ) validation of efficacy (3.44), level of EBM validation of safety (4.30), standardization of the product (5.37), efficacy based on personal experience (5.82), defined content(s) of the major allergen(s) in micrograms (5.96), scientific evidence for each single allergen (6.17), safety based on personal experience (6.32), ease of administration protocol (8.08), cost and terms of payment (e.g. instalments) (9.17), dose personalization (9.24), patient preference (9.25), ease of product storage (9.93), reimbursement (10.12), and availability of a helpline or on-line assistance from the manufacturer (11.89). These attitudes need to be taken into consideration by regulatory agencies as well as by producers.