Background: Allergic conjunctivitis was a chronic inflammatory disease, usually associated with rhinitis. Several modalities of treatment were available, but few studies mentioned of immunotherapy which might had benefits in chronic and severe cases.Objective: To evaluate efficacy and safety of local conjunctival immunotherapy (LCIT) using a mixed Dermatophagoides extracts for treatment of allergic conjunctivitis (AC)Methods: A prospective, double-blind and randomized controlled trial (RCT) was performed on eighteen patients with positive skin prick test (SPT) reactions to house dust mites. They were randomized into 2 groups: 1) treated with LCIT and 2) treated with balanced salt solution (BSS) as a control for a 6-month period. Allergen extracts were prepared in eyedrops and given once daily in LCIT group. Efficacy was assessed by clinical scores and conjunctival provocation test (CPT).Results: At 6 months, the CPT scores for the LCIT group reached statistical significance compared to the control group (p = 0.038), but there were no statistically significant differences in signs (p = 0.591), symptoms (p = 0.885) and medication scores (p = 0.338) between both groups. Patients in LCIT groupwere able to tolerate the allergen without developing any serious adverse events.Conclusion: LCIT treatment significantly reduced CPT scores which indicated that the patients were able to tolerate the antigen better than their counterparts. However, LCIT alone at short period did not alleviate symptoms and signs of allergic conjunctivitis from multiple allergens.