The occurrence of coarse woody debris (CWD) at sites of subnivean (under snow) access by martens (Martes americana) has not been quantified adequately, and must be better understood to provide suitable winter habitat management for the species. Consequently, we studied subnivean activity of martens in a subalpine forest in southern Wyoming to determine how subnivean space was accessed, and to examine microhabitat characteristics around entry sites. Martens used existing openings in snow, created primarily by logs at low snow depths and by small live spruce and fir trees at greater snow depths. Sites of marten subnivean entry had greater percent cover (P ≤ 0.01) and total volume of CWD (P ≤ 0.01), greater numbers of log layers (all P ≤ 0.02), greater volume of undecayed (P ≤ 0.05) and moderately decayed logs (P ≤ 0.02), less volume of very decayed logs (P ≤ 0.001), and fewer small root masses (P ≤ 0.001) than surrounding forest stands. Provision of sufficient CWD in winter habitat of martens may require specific effort, particularly in managed forests of the central Rocky Mountains.