The aim of this study was to analyze the effect of clone and site on poplar root colonization with ectomycorrhizal, arbuscular mycorrhizal and dark septated endophytic fungi. Studies were conducted in poplar clones' plantations of different age on sites Tomaševac, Banov Brod and Kupinovo. Poplar's root colonization rate of mensioned fungi was determined on clones "Bora", "Antonije" and "PE16/99". Significant effect of site on colonization with ectomycorrhizal fungi was determined as well as on ratio between colonization with arbuscular mycorrhizal and ectomycorrhizal fungi. Clones manifested significant differences in colonization rate with arbuscular mycorrhizal fungi.