Introduction: Immunotherapy has proven its efficacy in multiple randomized control trials (RCT) in treating allergic rhinitis (AR) as it induces induces long term remission after discontinuation and prevent new sensitization. Objective: Our aim is to look into earliest improvement of quality of life (QOL) in AR patient treated with Sublingual immunotherapy (SLIT). Methodology: Patients who were sensitized to dust mites (Dermatophagoides farinae, Dermatophagoides pteronyssinus and Blomia tropicalis) were enrolled into the study. All patients were treated with SLIT for 6 months. The patients were assessed using rhinoconjunctivitis quality of life questionnaires (RQLQ) and peak nasal inspiratory flow (PNIF) pre-treatment at 1, 3 and 6 months post SLIT. The usage of intranasal corticosteroids (INS) and antihistamine were documented in medication diary. The data for pre and post treatment for RQLQ results were analysed using paired T-test and medication diary were analysed using ANOVA test. Results: A total of 53 patients were enrolled in the study. The mean RQLQ score showed significant result at 3 and 6 months post SLIT (p<0.05). Significant improvement seen in the mean PNIF value pre-treatment (81.54 L/min ±29.36 ) compared to mean PNIF value at 3 months (92.0L/min ±29.03 ) and 6 months (96.13L/min ±26.67) post SLIT (p<0.05). The dependency of patients towards pharmacotherapy also showed a significant reduction at 3 and 6 months post SLIT (p<0.05). Conclusion: Our study showed a significant improvement of patients’ quality of life as early as 3 months of post SLIT treatment.