Young mice aged 4--6 weeks and old mice aged 24--26 weeks were inoculated with standard, single, oral doses of two strains of human pathogenic 'related' campylobacters and in vitro small intestinal solute absorption and fluid transfer measured 7 days after inoculation. Young inoculated mice showed significantly lowered D-glucose and D-galactose absorption; in old inoculated mice absorption of these solutes remained unaltered. In young inoculated mice absorption of D-glucose was uniformly depressed in the distal four-fifths of the small intestine; absorption in the proximal one-fifth remained unaltered. Fluid transfer from the entire small intestine or segments of intestine remained unchanged 7 days after inoculation.