An adjustable leg for supporting a table top whereby the height can be raised or lowered comprises a metal tube defining the leg within which is mounted a screw threaded rod. A square opening in one side of the wall of the tube exposes the teeth of a gear member which can be rotated and carries a screw thread for cooperation with the rod to raise and lower the table top. Collars on either side of the gear member provide bearing surfaces for axial movement of the rod and for rotational movement of the gear member. The gear member can have two separate axially spaced sets of teeth, one for cooperation with an electric motor drive gear and the other for cooperation with a manually operable ratchet device. The ratchet device and electric motor are alternatives and each of which can be mounted in a housing for clamping around the tubular leg.