<正> Endoscopic biopsies from the distal ileal mucosa in 366 subjects with suspectedlower gastrointestinal disease and 81 normal volunteers were examined comparatively withlight microscope

scanning electron microscope（SEM）and ilcoscopy.Mucosal atrophyof distal ileum were found in 21 cases.Endoscopically the atrophied ileal mucosa pre-sented a pale red colour and the twiggy vessels were distinct.The lumen of the distalileum was usually dilated.Histopathological and SEM study of the above 21 patientsand 81 normal volunteers was carried out.Heal biopsy samples were marked with Indianink on the mucosal surface

and serially sectioned after their orientation was defined.The range of villou height was 0-320 μm

averaging 185±164 μm in the ilcal mucosalatrophy group（IMAG）

whereas it was 370-500 μn

averaging 416±22 μm in thenormal volunteers.The difference between the normal group and the IMAG was signifi-cant

P<0.001

The atrophied ilcal mucosa could bc divided into four grades accordingto its villous height

our definition is as follows :Grade 0-from lower limit of normalvalue to 300 μm is a height which suggests that mucosal atrophy might bc present:Grade 1-300-200 μm is difincd as slight mucosal atrophy;Grade 2 200-100μm

moderate mucosal atrophy;Grade 3 from 100 μm to disappcarance of villi

severemucosal atrophy.Villous atrophy was found not in proportion to the cxtent of mucosalinflammation.Atrophied villi under microscope showed a shortened

battlement-like ap-pearance.Sometimes the villi had disappeared.Under SEM

the villi appeared shor-tened

papilla-like or gyrus-like.