Buckwheat (Fagopyrum esculentum, Moench), a herbaceous plant of the Polygonaceae family, does not have any affinity for the Gramineae family. It is commercially rated as a cereal, which has led to some misunderstanding concerning its use in gluten induced enteropathy or celiac disease. The effect of buckwheat flour ingestion by celiac patients was evaluated through the indirect immunofluorescence technique. Samples of serum were collected 30 days after the flour ingestion. Cryostat performed cuts of wheat and buckwheat grains were accomplished in order to compare the reactivity of their proteins and serum of celiac and normal patients. The assay revealed that the buckwheat flour presents no toxicity for the celiac patient and no anti-protein antibodies formation in the grain was observed for serum dilutions of 1:2 up to 1:32 with 0.15 M NaCl solution in 0.01 M phosphate buffer, pH 7.2 throughout the 30 day assay period. The results of the immunological assays showed that the buckwheat flour does not present toxic prolamines to celiac disease patients.