The prevalence of symptomatic CD in Switzerland is thought to be 1 in 1,000 inhabitants. As in other countries, oligo- and asymptomatic CD is being diagnosed with increasing frequency in all age groups. To assess the prevalence of asymptomatic CD in adolescents in eastern Switzerland. Between September 1999 and July 2000 total serum IgA titres, anti-endomysium IgA (EMA) titres and anti-human tissue transglutaminase IgA (hTTG) titres were measured in the serum of healthy 11- to 18-year-old Swiss lower and upper secondary school students. Of the 1,450 students (871 f = 60.1%, CI 95%) tested, 11 (10 f) had elevated levels of both EMA and TTG. The diagnosis of CD was confirmed in eight of these students by mucosal jejunal morphology (Marsh III); one exhibited normal histology. Two of the 11 students refused to undergo mucosal biopsy. None of the students, however, had symptoms suggestive of CD, nor were they stunted or underweight, and none of them had family members with known CD. All of the eight students with enteropathy went on a glutenfree diet and felt subjectively better than on a normal diet. Of the remaining students, 38 (2.6%) had family members with known CD. None of those with the relevant family history had elevated EMA or TTG levels. Asymptomatic CD is common. It occurs in 1 in 132 (0.75%) Swiss adolescents. The absence of subjectively recognisable symptoms suggestive of family history or other risk factors makes it difficult to diagnose this type of CD.