The specificity of the Pastorex Aspergillus latex agglutination test for the diagnosis of manifest aspergillosis is hampered by the occurrence of false-positive results. In order to prove whether or not the false-positive reactions may be caused by the uptake of the soluble galactomannan antigen from the environment, the presence of the antigen was tested in foods, air samples, antibiotics for therapeutic use and faeces. Reactions of the Aspergillus latex agglutination test were found in 15 (79%) out of 19 samples of meals prepared in a hospital kitchen, in five out of six canned vegetables from a supermarket, in all of six samples of pasta and rice bought in health shops, in the faeces of four bone marrow transplant (BMT) recipients and of four healthy subjects and in one and two batches of the antibiotics co-amoxyclav and piperacillin respectively. The concentration of the antigen in faecal material was calculated to be in the range of 1.2-38.4 micrograms g-1. It is concluded that the faecal galactomannan antigen may reach the circulation in patients with dysfunction of the intestinal mucosal barrier, e.g. BMT recipients, thus leading to diagnostically false-positive antigenaemia.