The study was conducted to determine the extent of illegal harvesting of timber species in Nyanganje Forest Reserve (NFR). Data on the extent of timber stocks harvested illegally in NFR were collected using both socio-economic and ecological surveys. Linear regression analysis showed that extraction of timber species in NFR mostly occurs at the roadside. The mean annual quantity of wood harvested illegally was estimated to be 6.2 m³ per ha. Although the NFR has high potential of timber species (standing stock of 119 m³ per ha), this is threatened by the high demand for timber species. Illegal harvesting of timber species is likely in NFR because the Government is providing few resources to safeguarding this reserve. Therefore, some arrangement from the Government is immediately needed to rescue this reserve and ensure its sustainability.