Serum IgA class reticulin antibody (RA) was found in 28 (97%) of 29 children with flat small bowel mucosa, and in low titer in four (2%) of 245 with normal or near normal mucosa on small intestinal biopsy. Thus the sensitivity of the IgA-RA fluorescent antibody test for screening of celiac disease was 97% and the specificity 98%. IgA-RA was superior to IgG-RA for the detection of celiac disease. During follow-up of patients receiving a gluten-free diet, the IgA-RA rapidly decreased and in most cases disappeared within a year, suggesting that the test may be useful for clinical follow-up of celiac disease as well.