This research aims to assess the practice pattern of Canadian emergency physicians for management of anaphylaxis and investigate the clinical predictors for biphasic reactions in children with anaphylaxis. We conducted two studies: a national survey and a multicenter Health Records (HR) review of emergency department visits. Of the 608 physicians surveyed, 340 (56%) responded. Overall, 211(62%) of the physicians correctly agreed that both hypothetical scenarios in the survey were consistent with anaphylaxis, and 206(61%) chose to administer epinephrine. In our HR review, we found five independent predictors of biphasic reactions: age 6-9 years (OR 3.60; 95% CI 1.5-8.58), time from onset of the anaphylactic reaction to ED presentation >90 minutes (OR 2.58; 95% CI 1.47-4.53), wide pulse pressure at triage (OR 2.92; 95% CI 1.69-5.04), treatment of the reaction with >1 dose of epinephrine (OR 2.7; 95% CI 1.12-6.55), and administration of inhaled salbutamol in ED (OR 2.39; 95% CI 1.24-4.62).