The aim of this study was to investigate the effects of Dryopteris filix-mas L., one of the indigenous fern species from Romania, and of a known As-hyperaccumulator, Peris cretica L., on As bioavailability at the roots-soil interface. The ferns were grown in pot experiments on two composite soils collected from two localities from north-western Romania, containing 108 mg kg^-1 dw and respectively 230 mg kg^-1 dw total As. The Diffusive Gradient in Thin-films (DGT) technique was used to study theroot-available As in soils, by measuring DGT-labile As fraction before and after plants grown. The Rratios between labile As concentration measured by DGT and As in soil solution were calculated and twodifferent behaviors were observed for the two ferns: in rizosphere of Pteris cretica L., R increased afterplants grown, which indicate a greater proportion of As in labile form, probably due to the Assolubilisation by fern roots, while contrary, in the rizosphere of Dryopteris filix-mas L. this ratiodecreased. Also, was observed that higher organic carbon (in its dissolved form) and phosphorous in soilenhanced As biovailability. Pteris cretica L. accumulated higher concentrations of As in the abovegroundpart, the translocation factor being about 7.5, but for Dryopteris filix-mas L. this factor was <1, thus thiscannot be considered As-hyperaccumulator. This study has also confirmed that DGT technique is asensitive tool for the evaluation of As mobility changes in the rizosphere of plants.