Chlamydia trachomatis was isolated from ten of 188 biopsies (5.3%) obt
ained from different parts of the lower digestive tract. Patients (mea
n age 37.0 years) presented with ulcerative proctitis, Crohn's disease
, mild colitis or ulcerative colitis. Seven rectal biopsies, two biops
ies from the sigmoid flexure and one caecal biopsy were positive for c
hlamydial isolation whereas all biopsies taken from the colon ascenden
s, transversum or descend ns and from the terminal ileum were negative
. We conclude that isolation of C. trachomatis is most effective from
rectal and sigmoidal biopsies and is a rare event from other sites of
the lower digestive tract.