(57) The present invention provides a foldable frame assembly, comprising a pair of complementary X-shaped side frames each having two bar members (1, 2, 1ʹ, 2ʹ) hinged together intermediate their ends to permit folding and unfolding in the plane of the X, the two side frames being mutually parallel and in register with each other; and a pair of centrally hinged transverse X-frame support stays, each having two substantially straight stay members (4, 5, 4ʹ, 5ʹ) hinged together at their mid points (6, 6ʹ) to permit folding and unfolding in the plane of the X which is perpendicular to the plane of the side frames. An end of each stay member is hinged to an end of a side frame bar member so as to permit pivoting both in the plane of the stay members and in the plane of the respective bar members, whereby folding and unfolding of the side frames causes simultaneous and corresponding folding and unfolding of the support stays. The foldable frame can form the basis for a foldable seat or a foldable chair.