Abstract Background The effectiveness of specific immunotherapy (SIT) in the treatment of allergic rhinitis has been supported by empirical evidence and clinical experience. Objective This report is an analysis of multiple studies involving patients with documented allergic rhinitis. Methods All studies of the effectiveness of SIT in the treatment of allergic rhinitis published in English between the years 1966 and 1996 were identified through a MEDLINE ® search. All prospective, single or double-blind, placebo-controlled studies were included in the analysis. One author (R.N.R.) extracted data from the studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model for a variety of clinical measures in studies that permitted the extraction of numbers of patients with positive and negative outcomes. Results Data were extracted from 16 studies of the clinical effectiveness of SIT in the treatment of allergic rhinitis, involving 759 patients (546 adults, 53 children, 160 all ages). In 15 (94%) of the studies, investigators concluded that SIT was effective. In the remaining study (the only one conducted in children), investigators concluded that SIT was not effective. Symptoms of allergic rhinitis were more likely to improve in patients receiving SIT than in the comparison patients (OR 1.81, 95% CI 1.48 to 2.23). Symptom medication scores were significantly lower in patients receiving SIT than in the comparison patients in all studies using such measures ( P < 0.05). Conclusion Results of this analysis support the conclusion that SIT is effective in the treatment of allergic rhinitis.