We tested non-invasive genetic methods for estimating the abundance of marten Martes americana using baited glue-patch traps to pull hair samples from individual animals. We divided our 800–km² study area into 3 × 3 km cells and put one hair trap in each cell. We trapped 309 sites for an average of 15 days each between 15 January and 14 March 1997. Based on tracks in snow and hair morphology, we captured hair from marten, red squirrels Tamiasciurus hudsonicus, flying squirrels Glaucomys sabrinus, short or long-tailed weasels Mustela erminea and M.frenata, and several unidentified mouse and vole species. Of 309 sites, 58% collected a marten hair sample while 8% of sites removed weasel hair. When roots were embedded in adhesive, a xylene wash was used to remove them before extracting DNA. All marten samples were genotyped at six microsatellite loci to identify individuals. Xylene-washed samples yielded similar genotyping success to samples that had never been exposed to xylene, and genotyping success increased with the number of hairs in the sample. Genetic data allowed 139 samples to be assigned to 88 individual marten, constituting 124 capture events during the four trapping sessions. The population estimate for our study area was 213 (95% Cl: 148–348) and the average capture probability was 0.15. The density of marten in our study area was 0.33/km² when inhospitable habitat was removed from the calculation. We believe hair sampling and genetic analysis could be used to measure population distribution, trend and size for marten, and perhaps also for other carnivores.