Background: Only a few randomized controlled trials have been carried out to evaluate various complementary treatments for allergic disorders. This study assessed the effects of the preseasonal use of birch pollen honey (BPH; birch pollen added to honey) or regular honey (RH) on symptoms and medication during birch pollen season. Methods: Forty-four patients (59% female, mean age 33 years) with physician-diagnosed birch pollen allergy consumed either BPH or RH daily in incremental amounts from November 2008 to March 2009. Seventeen patients (53% female, mean age 36 years) on their usual allergy medication served as the control group. From April to May, patients recorded daily rhinoconjunctival and other symptoms and their use of medication. Fifty patients completed the study. Results: During birch pollen season in 2009, BPH patients reported a 60% lower total symptom score (p < 0.01), twice as many asymptomatic days (p < 0.01), and 70% fewer days with severe symptoms (p < 0.001), and they used 50% less antihistamines (p < 0.001) compared to the control group. The differences between the BPH and RH groups were not significant. However, the BPH patients used less antihistamines than did the RH patients (p < 0.05). Conclusions: Patients who preseasonally used BPH had significantly better control of their symptoms than did those on conventional medication only, and they had marginally better control compared to those on RH. The results should be regarded as preliminary, but they indicate that BPH could serve as a complementary therapy for birch pollen allergy.