The effects of an aqueous extract of Artemisia princeps var. orientalis and two phenolic compounds on mycorrhizal colonization and plant growth have been investigated. Greenhouse studies showed that the inhibitory effect of the extract on mycorrhizal colonization and plant growth increased in proportion to the concentration of the extract. When the mycorrhizal test plants were treated with an increasing concentration of phenolic compounds, the mycorrhizal colonization in roots of the test plant and the plant growth were decreased. There were strong indications that mycorrhizal fungi mitigated the inhibitory influence of shoot extract of A. princeps var. orientalis and phenolic compounds.