Peanut avoidance is difficult and AE occur. We aimed to determine the incidence of AE in Canadian children with peanut allergy. Children with a physician-confirmed diagnosis of peanut allergy were identified from: 1) the Montreal Children's Hospital and 2) provincial and national food allergy advocacy organizations. Parents of participating children completed annual questionnaires regarding AE to peanut. Nine hundred seventy-one patients completed questionnaires at study entry and 271 at one year follow-up (only 350 were followed for one year post-entry and were eligible for the follow-up questionnaire). Mean age (SD) at diagnosis was 2.3 (2.0) years. One hundred forty-eight AE occurred in 127 children over 1178 patient-years, yielding an annual incidence rate of AE of 12.6% (95%CI, 10.6% to 14.8%). Fifty-nine reactions occurred at home, 27 at the homes of relatives, friends or neighbors, 13 in restaurants, 12 at school, including 9 in schools prohibiting peanut, 5 in daycare, and 32 at other or unknown places. Fifty-one reactions were mild (pruritus, urticaria, flushing and/or rhinoconjunctivitis), 78 were moderate (angioedema, voice change, coughing, nausea, vomiting and/or abdominal pain), and 19 were severe (wheezing, stridor, cyanosis and/or circulatory collapse). No treatment was administered for 13 mild and 13 moderate reactions. Epinephrine was used in only 22 of 97 moderate or severe reactions. Although increased awareness of peanut allergy in our cohort may have contributed to the lower rate of AE, most moderate and severe reactions were managed inappropriately. Therefore, better education of caregivers and patients regarding peanut allergy management is desirable.