Abstract: The invention relates to a seat for a chair for persons having hip and/or leg stiffness, the seat including at least one pivotable portion (1, 2) pivoting around a pivot axis (3) extending in the lateral direction of the seat, the forward edge of each pivotable portion forming part of the front edge of the seat, whereby each pivotable portion (1, 2) is arranged for pivoting movement between a substantially horizontal position and a position where it is directed forwardly and downwardly, a locking device (5) being arranged for locking each pivotable portions (1, 2) in the desired position. The object of the invention is to improve a seat of this kind, so that a person having hip and/or leg stiffness may have a better sitting position than is possible in previously known seats of this kind.