We estimated bark decomposition rates and compared them to wood decomposition rates of birch,Siberian fir, Siberian pine and Siberian spruce in the northern boreal forests of Komi Republic, Russia. Estimates were made based on the mass loss of bark attached to fallen and leaning logs. The proportional rate of bark mineralization was the same for Siberian fir, Siberian pine and Siberian spruce logs – 0.040 yr-1. The mineralization rate of birch bark was 0.009 yr-1. The bark turn-over time (t95) was 302, 224, 149, 140 and 117 years for birch, fir, spruce, Siberian pine with diameter more than 41 cm, and Siberian pine with diameter less than 40 cm, respectively.