Abstract: The invention concerns a lysis method for a biological sample comprising at least one micro-organism of the bacteria type, for releasing a nucleic material of interest belonging to said micro-organism, which consists in: providing in a container a biological sample in liquid medium; providing in said container at least one particulate material, relatively hard, and substantially inert with respect to the nucleic material; submitting the biological sample and particulate material mixture to a movement. The invention is characterised in that in combination, the selected movement is of the vortex type, and satisfies the following conditions: the particulate material consists of beads with diameter between 90 and 150 &mgr;m; and the apparent volume of the beads (Vb) and the volume of the liquid sample (Ve) are linked by the relationship Ve=&agr;. Vb, with &agr; ranging between 1.4 and 10 when the container is tubular in shape, and &agr; is not more than 2.