We studied the hospital records of patients with celiac sprue in order to determine how frequently hospital specialists failed to make the diagnosis. Over a 7 1/2-year period, 39 patients were diagnosed, 49% within the last 18 months of the study period. Fourteen patients (39%) had been referred to the hospital a total of 30 times with features suggestive of celiac sprue, yet without being successfully diagnosed: the delay between initial referral and diagnosis was > 6 years in nine of these patients. The diagnosis was made by gastroenterologists or other internists in 38 (97%) patients. Gastroenterologists had an 85% (33 of 39) diagnostic success rate, other internists 63% (five of eight), and surgeons 7% (one of 14). None of eight referrals to other specialists led to diagnosis. While a history of diarrhea was morel likely to lead to diagnosis, it was reported by only 59% (23 of 39) of patients at the time of diagnosis and at only 46% (32 of 69) of referrals; furthermore, it did not prompt correct diagnosis in 28% (nine of 32). Anemia was the sole manifestation of celiac sprue at 17 referrals, and correct diagnosis was made in only seven (41%), all by gastroenterologists. The perceived rarity of celiac sprue reflects its underdiagnosis. Diagnosis is still delayed even in patients with classic diarrhea, and there is still a failure to appreciate the possible manifestations of sprue, including anemia without gastrointestinal symptoms. Because patients may be referred to specialists other than gastroenterologists with symptoms arising from celiac sprue, a wider knowledge of its manifestations is called for.