Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy affecting captive and free-ranging cervids. Currently, tests for CWD in live animals involve relatively invasive procedures to collect lymphoid tissue biopsies and examine them for CWD-associated, protease-resistant cervid prion protein (PrP^CWD) detected by immunohistochemistry (IHC). We adapted an ultrasensitive prion detection system, protein misfolding cyclic amplification (PMCA), to detect PrP^CWD in Rocky Mountain elk (Cervus elaphus nelsoni) feces. Our PMCA reproducibly detected a 1.2×10⁷ dilution of PrP^CWD (a 10% infected brain homogenate diluted 1.2×10⁶-fold into 10% fecal homogenates), equivalent to approximately 100 pg of PrP^CWD/g of feces. We developed a semiquantitative scoring system based on the first PMCA round at which PrP^CWD was detected and fit a nonlinear regression curve to our serial dilutions to correlate PMCA scores with known PrP^CWD concentrations. We used this PMCA scoring system to detect PrP^CWD and estimate its concentration in feces from free-ranging elk from Rocky Mountain National Park, Colorado. We compared our results to PrP^CWD IHC of rectoanal mucosa-associated lymphoid tissue and obex from the same animals. The PMCA successfully detected PrP^CWD in feces from elk that were positive by IHC, with estimated prion loads from 100 to 5,000 pg PrP^CWD/g of feces. These data show for the first time PrP^CWD in feces from naturally exposed free-ranging elk and demonstrate the potential of PMCA as a new, noninvasive CWD diagnostic tool to complement IHC.