Patients with chronic cryptogenic hypertransaminasemia are at high risk of developing celiac disease (CD). In fact, among the various serological disorders, CD patients at onset frequently present hypertransaminasemia. In this study, we evaluated usefulness and reliability of the new test for antitissue transglutaminase (tTG) in screening for CD as well as in estimating the prevalence of CD in a population of blood donors presenting unexplained hypertransaminasemia at donation. Controls were 180 consecutive healthy donors without hypertransaminasemia and 20 CD patients with known antiendomysial antibody (EmA) positivity. Out of 22,204 blood donors over a period of 2 years, we found 258 subjects (1.2%) with cryptogenic hypertransaminasemia. Four of these subjects (1.5%) were positive for anti-tTG, but only 3 of them were positive for EmA. EmA were negative in all the remaining hypertransaminasemia subjects. In the control groups, anti-tTG antibodies were negative in all the 180 healthy donors without hypertransaminasemia, but positive in all the CD patients known to be EmA positive. 3 of the 4 subjects positive for anti-tTG, including 2 who were also EmA positive, underwent biopsy of the distal duodenal mucosa which showed a picture compatible with CD only in the 2 patients with concomitant EmA positivity. After 3 months of gluten-free diet, the serum transaminase values normalized in these 2 patients. In conclusion, the prevalence of CD in our blood bank population was lower than that reported in other similar studies, but the new test for anti-tTG showed a good sensitivity and reliability, and, therefore, it can be proposed as a first-level test in screening for CD in selected populations such as subjects with hypertransaminasemia.