Marsh’ classification of celiac disease or malabsorption syndrome sensu stricto is based on increased number of intraepithelial lymphocytes, as the first and constant sign/feature of the disease. Thereafter follow structural alterations of the mucous membrane, particularly of villous architecture, crypt height and enterocytes. According to the Marsh’ classification, type 0 corresponds to normal mucous membrane, and type 1, the infiltrative type, is characterised by an increase in intraepithelial lymphocytes (IEL), which amount to more than 40 lymphocytes/100 enterocytes. Type 2 has normal villous architecture, an increase in IEL numbers and crypt hyperplasia. Type 3, the destructive type, is characterised by villous atrophy and may be divided into three subgroups depending on the degree of the atrophy - mild, marked, and total (flat mucosa). Combination of these histopathological findings, patient’s history and clinical course may result in the definition of six „states“ of celiac disease. Marsh’ classification is helpful for an early diagnosis of the disease and should be applied in any case of the bioptical examination of the malabsorption syndrome. The disadvantage of this system, applied on formol-paraffin tissue sections, is impossibility of revealing disacharidases (particularly lactase) deficiency. From this point of view, histochemical detection of disacharidases should accompany the bioptical examination of jejunal mucosa.

        Key words: celiac disease - malabsorption syndrome - biopsy - histochemistry.