and It is necessary to screen the type of ectomycorrhizal, and to inoculum it into the seedlings before planting. thus, the objective of this project is to study the diversity ectomycorrhiza in denuded forest of Chulalongkorn University in kaengkoi district, Saraburi province. soil from the area was used as soil inoculum for Shorea siamensis and Dipterocarpus intricatus. when the seedlings were 6 month-old, morphological methods was characterized and infection rate was calculated. The results indicated that there are 2 types of ectomycorrhizal roots marphology in S. siamensis; ECM1 and ECM2, In ECM1 morphology, the ectomycorrhiza's roots were black, with monopodial-pinnate branching. and the infection rate was 36.90%. In ECM2 morphology. the ectomycorrhiza's roots were yellow with monopodial-pinnate branching. and the infection rate 11.65 %. As far the controlled group. ECM1's infection rate was 36.33%. and ECM2's. infection rate was 9.18 %. There were also 2 types of D. intricalus: ECM3 and ECM4, in ECM3 morphology. the ectomycorrhiza's roots were black with monopodial-pinnate branching. and the infection rate was 46.91 %. In ECM2 morphology, the ectomycorrhiza,s roots were yellow with monopodial-pinnate branching. and the infection rate was 11.88%. As far the controlled group. ECM3's infection rate was 32.73 %, and ECM2's infection rate was 11.70 %. The results showed that the diversity of ectomycorrhizal fungi in the experimented area is significantly low. It has very Limited species of ectomycorrhizal fungi and also lacks ectomycorrhizal fungi in terms of quantity. Consequently, seedlings need to be inoculated with ectomycorrhizal fungi before planting in this area.