A method and a device for separating a component, such as fibrin I from blood, by centrifugation. The method involves feeding of blood admixed an anticlotter to a first annular chamber in a device, where the annular chamber is defined by a cylindrical outer wall and a cylindrical inner wall, both walls extending coaxially about a common axis, as well as by a top wall and a bottom wall, where the top wall or the bottom wall is formed by a piston body displaceable within the first chamber. The method involves furthermore a centrifugation of the device about the said common axis followed by a resulting liquid fraction being transferred while influenced by the piston body to a second chamber defined by an outer cylindrical wall, which extends coaxially with said common axis. As a result the liquid fraction present in the second chamber is caused to be further separated by a continued centrifugation and addition of suitable compositions promoting the separation and returning of the non-utilizable portion to the first chamber. In addition, the portion of the liquid fraction remaining in the second chamber is transferred to a liquid-receiving container through a filter optionally after addition of a solvent. The portion of the liquid fraction remaining in the second chamber prior to the transfer to the liquid-receiving container is transferred to a third chamber coaxially accommodated with the other chambers, and the liquid now present in said third chamber is caused to pass through an annular filter during the centrifugation so as to enter an annular outer compartment which is adapted to be connected to the liquid-receiving member.