The effect of breastfeeding on the development of allergic rhinitis and other atopic conditions has been assessed in many studies but remains controversial. To elucidate this issue, a systematic review was conducted of prospective studies that evaluated the association between exclusive breastfeeding during the first 3 mo after birth and allergic rhinitis. The 1966-2000 MEDLINE databases were searched and the reference lists of relevant articles were reviewed according to predetermined inclusion criteria. The methodological aspects of each study, duration and exclusivity of breastfeeding, outcome measures, control for potential confounding variables and other factors were assessed, and estimates of the association between breastfeeding and allergic rhinitis were abstracted independently by the investigators using a standardized approach. Six prospective studies met the inclusion criteria. The summary odds ratio for the protective effect of breastfeeding was 0.74 (95% confidence interval 0.54-1.01). The effect estimate in studies of children with a family history of atopy was 0.87 (95% confidence interval 0.48-1.58). CONCLUSION: Exclusive breastfeeding during the first 3 mo after birth protects against allergic rhinitis in children, both with and without a family history of atopy. The protective association, although of borderline statistical significance, was substantial. Larger prospective studies with strict methodology and longer periods of follow-up are needed.