An influence was studied in experiment of intragastrically administrated milk cream contaminated with mould fungi spores on systemic anaphylactic reaction gravity in Wistar albino rats sensitized with egg albumin (EA). During 28 days sensitized rats intragastrically received cream containing 10(3) or 10(6) colony forming units of 5 fungal species in one cm3. After being challenged rats developed mild anaphylactic shock followed by elevation of small intestinal permeability for macromolecular tracer polyethylene glycol 4000. An increase of small intestinal permeability was also noticed in unsensitized rats that were fed with cream contaminated with 10(6) spores per cm3. Unexpectedly these effects were not additive: the intestinal permeability in sensitized rats decreased at maximal level of contamination. This may be explained by strengthening of gastrointestinal motility in these animals. Significant elevation of antibody production against EA was revealed in sensitized rats that received cream contaminated by spores at high level. The data obtained signify that milk products fungal contamination that could not be revealed by sense may nevertheless have negative impact on intestinal barrier function and sensitization.