Abstract: A centrifuge rotor including a sample carrier (1) enclosing within an outer housing (7,8) and being rotatable about a principal axis of rotation of the rotor, the sample carrier (1) having a peripheral zone for holding sample tubes (6) in an orientation parallel to the said axis when at rest and the sample carrier being capable of deflecting to enable sample tubes (6) to swing out under the effect of centrifugal force. The swinging out of the tubes (6) is constrained and controlled by the arrangement of the sample carrier (1) and contact between the tubes (6) and outer housing (7,8).