Feces are increasingly valued as practical samples for molecular diagnosis of infectious disease. However, extraction of polymerase chain reaction (PCR) quality DNA from fecal samples can be challenging because of coextraction of PCR inhibitors. Because the type and quantity of PCR inhibitors is influenced by diet, endogenous flora, and concurrent disease, it is unlikely that extraction method performance with human feces can be directly extrapolated to that of domestic cats. In the present study, 4 commercially available DNA extraction methods were examined for their influence on the sensitivity of PCR for the detection of Tritrichomonas foetus in feline stool. DNA was extracted from serially diluted feline-origin T. foetus trophozoites in the absence or presence of feline feces. The ZR Fecal DNA kit was identified as affording the greatest analytical sensitivity and reproducibility and was able to detect >or=10 T. foetus organisms per 100 mg feces in 100% of PCR reactions. Further, the identified extraction method could be completed in the shortest time of all kits tested.