An experiment in which perennial ryegrass (Lolium perenne L.) was grown in solution cultures containing various forms of radiosilver (^110mAg) is ptake of labelled Ag from solutions containing either AgNO₃, Ag₂SO₄, AgCH₃COO, Ag-humic acid (HA) or Ag-fulvic acid (FA) complexes is compared. In each case concentrations of Ag in the plant roots was several fold higher than in the plant shoots. However the Ag concentration in roots from the Ag-HA preparations was only about 5% of that from the AgNO₃ solutions; from Ag-FA it was 18%. Transport index values were highest for plants grown in the Ag-HA solution, indicating greater mobility of Ag within these plants. Preliminary data for a selective extraction procedure performed on Ag-HA preparations suggest sorption onto various active sites. The relevance of these findings to the cycling of Ag within soils is discussed.