Abstract: The invention relates to a method of rehabilitating soil and/or underground water in a volume of polluted soil. The method comprises the following steps: moving a boring tool in the volume, the tool being suitable for cutting up the soil and mixing it uniformly in said volume; and simultaneously with the mixing, injecting a treatment agent into the soil mixed with said tool, so that said treatment agent is dispersed uniformly in the volume, said treatment agent comprising at least one of the following agents: a gaseous fluid that is not solely chemically reactive; a chemically reactive agent constituted by a chemical substance that is oxidizing, reducing, or neutralizing; and a reactive agent constituted by a population of microorganisms or by a microorganism culture medium; whereby the soil and/or underground water is/are rehabilitated in situ.