From 1969 to 1973 171 peroral intestinal biopsies were carried out at the Children's Hospital Tübingen using the Crosby-Kugler capsule and the Watson intestinal biopsy capsule of paediatric size. The dissecting microscope findings were compared with the histological findings. The former correlated in stage II and III, according to the Shmerling scale, with the histological findings. Findings under the dissecting microscope, stage I, did not correlate in all cases with the histological findings. It is supposed that this results from either an inaccurate orientation or from inadequate sectioning. The plane of sectioning must be parallel to the villi. If the plane of sectioning is not parallel to the villi, the slender villi under the dissecting microscope look like plump villi when examined histologically. It is supposed that this results in a greater number of plump villi and a smaller number of slender villi in the histological findings compared with the dissecting microscope findings. The correspondence of slender villi examined under the dissecting microscope and those which are histologically examined in about 25 to 100%.