Aims: Tempe is a traditional fungal fermented food made from soaked and cooked soya beans. It has been associated with antidiarrhoeal characteristics. This study investigated potential inhibitory effects of tempe on enterotoxigenic Escherichia coli (ETEC) K88. Methods and Results: Soya beans were soaked, cooked and subsequently fermented using several Rhizopus spp. Water-soluble filter-sterile extracts were tested for their ability to inhibit growth of E. coli and several indicator microorganisms and to inhibit adhesion of ETEC K88. Antimicrobial activity was found against Bacillus stearothermophilus only. ETEC K88-induced haemagglutination of hamster red blood cells was strongly inhibited by a number of tempe extracts and hardly by the cooked soya bean extract. Furthermore, several tempe extracts were able to inhibit adhesion of ETEC K88 to piglet small intestinal brush-border membranes. Conclusions: Tempe appeared to interfere with ETEC K88 adhesion rather than showing growth inhibitory properties. Significance and Impact of the Study: The results indicate that tempe could exert an antagonistic effect against ETEC through inhibition of adhesion and might therefore have a protective effect against ETEC K88 infection in pigs. Hence, tempe could have potential to use as a feed supplement in the diet of weaned piglets.