A study was conducted to assess the impacts of elevation, tree species and management on carbon stock on the slopes of Rungwe Mountain in Tanzania. Twenty 15 m radius plots with trees of DBH >10 cm were used to collect trees measurements as well as soil samples at depths of 10 cm, 20 cm and 30 cm. Tree data collected were calculated and analyzed for tree biomass and carbon by using the Tree Biomass Equations (TBE) while soil samples were analyzed for total soil carbon using oxidative reduction method in which soils were combusted at about 600˚C in a muffle furnace to released CO2 and SO2 gases carried by the oxygen flow into cells. The results showed that aboveground carbon content increased with altitude ranging from 9.2 t/ha at 2031 m to 561.7 t/ha at 2312m.a.s.l due to little forest disturbance at high altitudes. However, the trend changed drastically at 2312 m.a.s.l. Soil carbon content tended to increase down the slope ranging from 3.8 t/ha at 2.312 to 4.7 t/ha at 2031 m.a.s.l, respectively. In general, there is limited awareness on sustainable management of forest resource in the study area. It is necessary to empower local communities to monitor and manage their forest resources so that they can contribute to climate change mitigation and income generation through carbon trade under REDD initiative.