In the present study, we investigated the outcomes of sublingual immunotherapy (SLIT) in house dust mite-induced allergic rhinitis (HDM-AR) patients. In this prospective, multicentric study, 186 patients with AR who had positive skin prick test results for HDMs were included. The patients were administered SLIT using Staloral 300 for 1 year. Evaluation of the patients regarding symptom scores, clinical findings and Rhinitis Quality of Life Questionnaire (RQLQ) scores was performed at baseline, and then at 6 and 12 months of therapy. Our results showed that, for all of the evaluated items (symptom scores, clinical findings and RQLQ scores), 12-month values were significantly lower than those at 6 months and baseline. Similarly, 6-month values were significantly lower than those at baseline. There were no complications in any of our patients. SLIT for HDM-AR is a treatment modality that can be used safely. We obtained better results than expected, and the treatment showed a positive psychological effect; the patients believed that SLIT was the final step of treatment and, which made them feel better.