Sublingual immunotherapy with monomeric carbamylated allergoid (LAIS) is an effective and well tolerated treatment of respiratory allergy. The aim of the present study was to correlate the efficacy of two maintenance doses (1000 AU vs 3000 AU) of LAIS with the immunological modulation of allergen-driven Th1, Th2 and T regulatory cytokines produced in vitro by PBMCs, in patients suffering from mite allergic rhinitis. Forty-eight consecutive patients with mite allergic rhinitis were recruited. Patients were randomly assigned to group A (n=24) or group B (n=24), respectively receiving 1000 AU or 3000 AU weekly during one-year maintenance phase. Each patient was evaluated for rhinitis severity (ARIA protocol), and for drug consumption at the time of the inclusion and after 6 and 12 months of treatment. Patients were also asked to report the perceived severity of the disease and the tolerability of the treatment in a visual analogical scale (VAS). Before and at the end of the treatment allergen-driven release of cytokines by PBMCs in vitro was measured. After 1-year treatment, a statistically significant reduction of all clinical parameters was observed in all patients, associated with reduction of IL-4 and increase of INF-γ secreted in vitro by mite-challenged PBMCs. Notably, the group treated with the higher dose showed significantly better clinical and immunological results. The efficacy of LAIS is correlated to the immune modulation in a clear dose-dependent effect.