We examined whether the Tyzzer's disease organism, Clostridium piliforme, could be detected in feces by PCR. If the organism could be detected in feces, a diagnosis could be made without sacrifice of the animal. Using the RT strain of C. piliforme, we found that a C. piliforme band could be detected when there were > or = 1 x 10(0) bacteria present in the PCR solution, but the presence of fecal extract in the solution depressed the sensitivity 10 fold. Nevertheless, we could detect the C. piliforme-specific band in fecal extracts from rats in a naturally infected colony, and concluded that the use of PCR to detect C. piliforme DNA in fecal extracts would be a useful diagnostic technique.