The An-Ident strip system (Analytab Products Inc., St-Laurent, Quebec, Canada) was evaluated for its ability to differentiate Treponema hyodysenteriae from Treponema innocens. Of the 20 tests included on this strip, 15 yielded identical results for the two species. Among the other five assays, none could be considered as a positive discriminator for the two species. However, when an indole spot test with 1% p-dimethylaminocinnamaldehyde was used in parallel, all reference strains and 97% of the isolates of T. hyodysenteriae were positive, whereas all isolates of T. innocens were negative. Our results indicate that An-Indent is of little value for the differentiation of the two species. Our results also suggest that a rapid and simple differentiation between T. hyodysenteriae and T. innocens can be achieved by using the hemolysis and ring phenomenon tests in conjunction with an indole spot test.