Globally it is recognized that the productive capacity, energy potential and capability to sequester carbon of forests can be conveniently indicated by the forest biomass and its carbon stocks. For the first time, present study explored the timberlines of Khangchendzonga National Park, Eastern Himalaya, India, with an aim to assess the status of biomass and carbon stock. Along 3800 m asl to 4000 m asl, in Dzongri landscape, we assessed nine major timberline sites for the estimation of total basal area, aboveground biomass, belowground biomass, total carbon and stem density. The total basal area varied between 99.55±1.90 and 4.50±2.41m2 ha-1. The total above ground biomass differed between 279.25±3.04 and 15.35±7.38Mg ha-1, while the total below ground biomass ranged between 144.76±8.10 and 9.85±4.82Mg ha-1. The total carbon content estimated between 195.03±2.32 and 11.59±5.61 Mg ha-1. Among the studied environmental factors, elevation and humus were observed the determining factors for the tree growth and forest composition in the study area. The present investigation in the timberlines offers a potential platform for long term monitoring of climate change induced changes.