The objective of this study was to develop polymerase chain reaction (PCR) assays for detection of Baylisascaris procyonis eggs and larvae in fecal, environmental, and tissue samples. We have optimized conventional and real-time PCR assays for B. procyonis using the mitochondrial cytochrome oxidase 2 gene as the target for amplification. The lower limit of detection of the parasite genomic DNA was 10 pg in the conventional PCR and 100 fg in the real-time PCR. In both PCR assays, specific amplification of a 146 bp product was achieved with DNA extracted from a single in vitro hatched B. procyonis larva and also from canine fecal samples spiked with as few as 20 unembryonated B. procyonis eggs per gram of feces. The PCR assays were successfully used for detection of B. procyonis eggs and larvae in fecal, environmental, and tissue samples. No DNA amplification was seen when the genomic DNA of related ascarids (including B. transfuga ) and a hookworm was used as template in the PCR; however, amplification was seen with the very closely related B. columnaris .