Abstract The Andean (spectacled) bear (Tremarctos ornatus) is the only extant species of bear in South America. This species is considered Vulnerable by the International Union for Conservation of Nature (IUCN), although current population sizes are unclear. To study Andean bears using DNA and non-invasive sampling, we screened 13 microsatellite loci using DNA extracted from blood, saliva, hair, and feces from 16 captive bears. Polymorphic loci were tested with samples from wild bears using DNA extracted from hair and feces collected in the Oyacachi territory inside the Cayambe-Coca Reserve in Ecuador during 2000 and 2001. Ten loci produced reliable results and were polymorphic with a mean of 4 alleles/locus. A minimum of 7 loci were needed for individual identification of wild bears using a probability of identity for siblings PID(sib) threshold of <0.01. Andean bears in the Oyacachi territory had moderate levels of genetic diversity (expected heterozygosity, HE = 0.45). Although genotyping success rat...