SLIT has been considered to have more advantages than SCIT in treating allergic rhinitis. Allergic rhinitis caused by cotton dust were concerned in Viet Nam. The study aimed to evaluate the effectiveness of SLIT in patients with allergic rhinitis caused by cotton dust. Materials and methods: We used standard cotton dust allergen to treat patients with allergic rhinitis caused by cotton dust in 3 years. The functional symptoms, physical symptoms and igE, igG4 concentration, prick test were compared before and after treatment, and adverse effects were recorded. Results: Before treatment, all patients had symptoms with severe or moderate level. After treatment, 98.1% of patients no longer had nose itching; 100% of patients had mild or no sneezing; 100% of patients did not suffer from runny nose or had in mild degree; 100% of patients did not suffer from nasal congestion or had in mild degree. The condition of nasal mucosa and inferior turbinate were also significantly improved (73,1% and 78,85% turned normal, respectively). For subclinical symptoms, the positive skin prick test, the serum IgE concentration in the patients decreased statistically, p < 0.001 and the serum IgG4 level increased statistically with p < 0.001.