It is well known that the house dust mites (HDMs) are the most common and potent inhalant allergens worldwide and the allergen immunotherapy (AIT) can efficaciously and safely ameliorate the allergic symptoms. Different formulations and routes of HDMs AIT have been achieved symptomatic improvement with mite allergic rhinitis (AR) and/or asthma. The object of the present article is to observe the efficacy and safety of oral immunotherapy (OIT) by enteric-coated capsules (EC) of Dermatophagoides farinae allergen (Df) with mite AR. A year of single blind placebo trial was applied. A total of 54 AR patients aged 25.8 in average with/without asthma and skin prick test (SPT) positive in HDMs were selected into either active or placebo groups. The OIT started with 5 days of dose rush induction, succeeded by a maintenance dose for 12 months. The efficacy of the treatment was assessed by symptomatic evaluation and laboratory in vivo and in vitro parameters of preimmunotherapy (pre-IT) and post-immunotherapy (post-IT) statistically. The patients each received a total accumulative dose of 16 715BU Df protein nitrogen, and 87.5% (21/24) subjects achieved symptomatic improvement. The post-IT symptom scores decreased (t=11.07, P<0.001); visual analog scale (VAS) decreased (t=10.68, P<0.001); number of patients required symptom-medication decreased from 23/24 to 3/24 cases (χ²=33.57, P<0.001); SPT wheal sizes of both Df and Dp significantly reduced (Df t=2.64, P=0.015 and Dp t=6.01, P<0.001); nasal provocation test (NPT) with the antigen tolerance elevated more than 3 times (χ²=9.65, P=0.008). The only unchanged parameter was the tIgE levels (P=0.07). The parameters of placebo group were changed but not significant statistically or negligible. There were no local or general adverse reactions in both groups happened in the one year course of OIT. It is concluded that the newly designed formulation and route of clinical administration by Df EC OIT with AR were comparable to that of Df sublingual IT. The new formulation is more convenient and promising approach to treat AR.