The dynamics of expression of some genes responsible for phosphorus transport (PT1, PT2, PT4, ATP1) at different developmental stages of Medicago lupulina in roots inoculated and uninoculated with AM fungus were analyzed. The levels of MtPT1 and MtPT2 transcripts were decreased under condition of AM symbiosis development. For the first time it is in M. lupulina AM roots that MlATP1 expression has been analyzed. The dynamics of AM-specific MlPT4 and MlATP1 expression depended on developmental stage of the host plant. The key changes in gene expression were observed at the stemming stage of M. lupulina plants.