Serum concentrations of primary bile acids (BAs) were determined in the course of celiac disease and in healthy age-matched controls. Determinations of BAs were made by radioimmunoassays after an overnight fasting and for 4 h postprandially after intake of a standardized test meal. In untreated celiac disease presenting with subtotal villous atrophy, peak concentrations of primary BAs were significantly delayed and serum levels were significantly higher than in controls. Small but significant abnormalities persisted after a period of gluten-free diet despite a normalization of mucosal morphology. Slightly pathological standard liver function tests in five patients were related to increased fasting levels but not to the postprandial pattern of BAs, indicating that the observed abnormalities postprandially were not related to liver disease. Further studies simultaneously focusing on deconjugation mechanisms, absorption, and pool sizes of BAs are required to explain the postprandial BA pattern under the course of celiac disease.