Objective: While there is general agreement that patient education is essential for compliance, no objective tools exist to assess knowledge in children and parents of children with endocrine disorders. We aimed to design and validate a Pediatric Endocrine Knowledge Assessment Questionnaire (PEKAQ) for congenital hypothyroidism, Hashimoto's thyroiditis, isolated growth hormone deficiency, Graves' disease, and congenital adrenal hyperplasia. We evaluated baseline knowledge of children and parents of children with these disorders and assessed impact of educational intervention. Methods: At baseline, 77 children (12-18 years) and 162 parents of children 1-18 years participated in this prospective intervention study. Educational handouts for five targeted disorders were designed. Following one-on-one educational intervention, 55 children and 123 parents participated. Baseline and post-intervention knowledge scores were compared using McNemar's test. Results: Adequate multi-rater Kappa measure of agreement was achieved for children's (0.70) and parent's (0.75) PEKAQs. Flesch Reading Ease Score for both PEKAQs (15 questions each) was 65. Post-intervention, significantly higher proportion of parents and children answered majority of questions correctly (p<0.05). Sixteen percent more parents and 22% more children knew their diagnosis correctly (p<0.05). Significant improvement was noted among all participants regarding reason for treatment, steps to take in a situation of missed dose, exercise and diet with these disorders, and long-term prognosis. Parent's knowledge score was an independent predictor of child's score. Conclusions: To our knowledge, this is the first validated PEKAQ that can be used widely in pediatric endocrinology clinics. We noted significant improvement in knowledge of children and parents of children with endocrine disorders.