Objectives: The transglutaminase (TG) antibody test is accurate in identifying celiac disease in symptomatic children. We sought to determine the positive predictive value of this test in asymptomatic children at genetic risk for celiac disease. Study design: Asymptomatic children with a genetic risk for celiac disease were studied to investigate the relationships between TG antibody titer, small bowel histology, growth, and clinical features. Small bowel biopsy histology was graded by using the system of Marsh. Results: Of 30 children with a positive TG antibody test result, 21 (70%) had definite (Marsh score 2 or 3) and 4 (13%) had possible (Marsh score 1) biopsy evidence of celiac disease. TG antibody titer correlated with Marsh score (r = 0.569, P <.01). There was an inverse correlation between Marsh score and height z score (r = –0.361, P =.05). Conclusions: In this group of asymptomatic children screened because of a genetic risk, TG antibodies have a positive predictive value of 70% to 83% for biopsy evidence of celiac disease and may identify children before clinical features of celiac disease develop. (J Pediatr 2000;137:356-60)