A total of 109 Escherichia coli isolates from piglets with diarrhoea, that had previously been shown to be enterotoxin producers, but negative for the adhesive fimbriae K88, K99, 987P and F41 were tested for the presence of more recently characterised fimbriae. Testing was done by immunodot assay with absorbed polyclonal antisera against Av24 and F107 fimbriae, and unabsorbed polyclonal antiserum and monoclonal antiserum against 2134P fimbriae. Strains were also tested by polymerase chain reaction for the presence of genes encoding the major subunit of F107 fimbriae. After elimination of possible non-specific reactions, antisera testing produced 10 strains positive with all 4 antisera, 1 strain that reacted with all antisera except F107, 2 strains that reacted with all antisera except the 2134P monoclonal, 3 strains that reacted with 2134P polyclonal and F107 and 2 that reacted with F107 only. The PCR testing confirmed the results of the antisera, but also produced an additional 14 positive strains, giving a total of 30% of the strains tested reacting positively by PCR. Furthermore, all 33 isolates positive by PCR came from pigs that were older than 1 week, which is 45% of the 72 isolates tested which came from older pigs.