OBJECTIVES:: In a Swedish celiac disease screening study (Exploring the Iceberg of Celiacs in Sweden), we systematically reviewed the clinical diagnostic procedures with the aim to evaluate the diagnostic accuracy and to take advantage of lessons learned for improving diagnostic routines. MATERIALS AND METHODS:: A school-based celiac disease screening study involving 5 Swedish centers, with 10,041 invited 12-year-olds with 7567 consenting participation. All 192 children with elevated serological markers were recommended to undergo small-bowel biopsy, performed and evaluated according to local clinical routines. All of the mucosal specimens were reevaluated by 1 and, when needed, 2 expert pathologists to reach diagnostic consensus. RESULTS:: Small-bowel biopsies were performed in 184 children: 130 by endoscopy and 54 by suction capsule. Endoscopic biopsies were inconclusive in 0.6%, compared with 7.4% of biopsies by suction capsule. A patchy enteropathy was found in 9.1%. Reevaluation by the expert pathologist resulted in 6 additional cases with celiac disease and 1 cleared. Sixteen children with normal or inconclusive biopsies, 4 after endoscopy, and 12 after suction capsule were endoscopically rebiopsied, resulting in another 8 cases. The celiac disease prevalence of 30 of 1000 (95% confidence interval 26-34) was not statistically different from that previously reported. CONCLUSIONS:: The present review revealed the importance of controlling each step of the diagnostic procedure. Several cases would have been missed by relying only on local routines. To improve the quality of childhood celiac disease diagnostics, we recommend multiple endoscopic biopsies from both proximal and distal duodenum and standardized evaluation by a pathologist with good knowledge of celiac disease.