Abstract. Daramola JO, Adesuyi FE, Olugbadieye OG, Akinbowale AS, Adekunle VAJ. 2020. Rate of timber harvest and the effects of illegal activities on forest conservation in Southwestern Nigeria. Asian J For 5: 8-16. Availability of accurate data on timber harvest is very important for sustainable forest management. These data are not readily available, making forest management more complex. This study aimed at investigating the rate of timber harvest, illegal activities and its impacts on forest conservation in Osun State Forest Reserves. The selected reserves were Shasha Forest Reserve (SFR), Ago-Owu Forest Reserve (AFR), and Ikeji-Ipetu Forest Reserve (IFR). Data were collected using two sets of semi-structured questionnaires. One for the forest community dwellers and the other for forest officers. Simple random sampling was used to select 120 respondents from the population of concessionaires, saw millers, rural community dwellers, taungya farmers and the government officers in the study area. Secondary data was collected and compiled from the State Forestry Department to provide results for timber harvested only in SFR from January to July, 2019. The results revealed that SFR is under massive timber exploitation, as illegal logging and timber processing are the most prevalent driver of exploitation in this area; while AFR and IFR are degraded forest reserves marred with grazing and poaching, and illegal logging, respectively. The impacts of the illegal activities on forest conservation were categorized under economic, social, and environmental impacts. The most exploited species in SFR were Celtis spp. (3024 stems), Ricinodendron heudelotii (1789 stems), and the least exploited was Anthocleista spp. (3 stems). The study showed that many economic tree species that contribute to national development and rural livelihood have been exploited from the study sites and therefore recommend that timber harvest be carried out on a sustainable basis.