An adjustable prosthesis joint, such as a prosthesis ankle or a prosthesis foot, and intended primarily for causing setting of the angular relation between an attachment means (4) forming part thereof for affixing the prosthesis joint (1) to a cooperating body part, and a detail (17) being angularly displaceably connected thereto, whereby the prosthesis joint is provided with means adapted to be actuatable to permit or to prevent such angular displacement, respectively, whereby said means is constituted by two communicating chambers (3a, 3b) containing a flow medium, with a shiftable valve (13) provided between the chambers, and at least one body designed as a piston (8, 9), rotatably arranged in relation to said chambers and movably arranged therein and adapted to permit flow of flow medium between the two chambers, when the valve is open and under influence of an external shifting force being displaced in said chambers (3a, 3b) in order to alter the relative sizes thereof.