Oral food challenge is a definitive diagnostic test for immediate and occasionally delayed adverse reaction to foods. The gold standard for diagnosing food allergy is still the double-blind, placebo-controlled food challenge, but it is time-consuming, expensive and troublesome for physician and patients. Open oral food challenge controlled by trained personnel is useful and sufficient methods when concern of bias is low. We aimed to provide a practical guideline for oral food challenge in children for the diagnosis of suspected food allergy or the evaluation of food tolerance. We considered reasons, types, indications, contraindications, risks, benefits, detailed methods, practical performance, interpretations of test results, and treatments for the adverse reactions of oral food challenge.