context: celiac disease, one of the best-known autoimmune human leukocyte antigen-dependent disorders, has a relatively increased prevalence in first-degree relatives. objective: to determine the prevalence of celiac disease in siblings of patients with confirmed celiac disease. methods: siblings of confirmed celiac disease patients in our center were identified and enrolled in this study. their serum immunoglobulin a and tissue transglutaminase antibody-enzyme-linked immunosorbent assay (anti-tissue transglutaminase, immunoglobulin a, and immunoglobulin g) were measured and multiple endoscopic duodenal biopsy specimens were obtained with parental consensus. celiac disease was confirmed by observation of characteristic histological changes. results: a total of 49 children (male, 29; female, 20; age, 2-16 years) with confirmed celiac disease in a pediatric gastroenterology ward were studied from 1999 to 2006. we found 30 siblings (female, 16) all shared in both parents. the only measurement available was for immunoglobulin a tissue transglutaminase antibody. a duodenal biopsy was performed in all 30 siblings. clinical findings such as abdominal pain, fatigue, growth retardation and diarrhea were found in 53.3% of the completely studied siblings, and positive serology without histological changes was identified in four cases. both serology and biopsy (confirmed new cases) were positive in 2 of the 30 siblings. conclusion: high prevalence of celiac disease among siblings of patients with confirmed celiac disease necessitates serologic screening (and confirmatory biopsy if indicated) in families having celiac disease. it is advantageous to diagnose the disease as soon as possible because early diagnosis and diet intervention may prevent serious complications such as growth retardation, short stature, chronic diarrhea, and malignancy.