The efficacy and safety of sublingual immunotherapy (SLIT) are currently supported by clinical trials, metaanalysis and post-marketing surveys. Practice parameters for clinical use of SLIT are proposed here by a panel of Italian specialists, with reference to evidence based criteria. Indications to SLIT include allergic rhinoconjunctivitis, asthma, and isolated conjunctivitis (strength of recommendation: grade A). As to severity of the disease, SLIT is indicated in moderate/severe intermittent rhinitis, persistent rhinitis and mild to moderate asthma (grade D). SLIT may be safely prescribed also in children aged three to five years (grade B), and its use in subjects aged more than 60 years is not prevented when the indications and contraindication are ascertained (grade D). The choice of the allergen to be employed for SLIT should be made in accordance with the combination of clinical history and results of skin prick tests (grade D). Polysensitisation, i.e. the occurrence of multiple positive response does not exclude SLIT, which may be done with the clinically most important allergens (grade D). As to practical administration, co-seasonal, pre co-seasonal, and continuous schedules are available, being the latter recommended for perennial allergens or for pollens with particularly prolonged pollination, such as Parietaria (grade D). For pollens with relatively short pollination, such as grasses and trees (cypress, birch, alder, hazelnut, olive) the pre coseasonal and perennial schedules are preferred (grade C). The build-up phases suggested by manufacturers can be safely used (grade A), but they can be modified according to the patient’s tolerance (grade C). A duration of SLIT of 3-5 years is recommended to ensure a long-lasting clinical effect after the treatment has been terminated (grade C).