Sublingual immunotherapy(SLIT) has received increasing attention as a treatment for asthma due to house-dust mites. The precise mechanisms of SLIT remain unclear, but SLIT has been shown to modify the balance of Th1/Th2, increase IgG4 and decrease IgE. The allergen is captured within the oral mucosa by Langerhans-like dentritic cells, suggesting that such cells are prone to induce tolerance. Increasing data support the safety, efficacy and good compliance with SLIT. However, the precise mechanisms, optimal dosage and duration of SLIT require further investigation.