The Andean bear (Tremarctos ornatus) is found throughout the Andes Mountains from Venezuela to Bolivia. However, little is known about its distribution and range in southern areas, including Argentina. Our objective was to develop a genetic marker to identify this species by analysis of non-invasive samples (i.e., hair or feces). We designed a primer pair to amplify a 115–base-pair fragment within cytochrome b of mitochondrial DNA. We successfully amplified the expected fragment in samples from Argentina (collected during 2 periods [1993 and between 2006 and 2008]) having sequences highly similar to Andean bear reference sequences in GenBank; and we identified 2 haplotypes in samples from northwest Argentina. We confirmed the presence of Andean bears in Argentina, which extends the known southern distributional limit about 150 km. Further studies employing our approach will allow for a comprehensive assessment of the potential distribution and southernmost range of this species.