An apparatus for magnetic resonance imaging of patients with limbs, particularly lower limbs, under natural stress, which apparatus includes a magnet structure having an open or closed annular shape, and a predetermined axial extension, which structure delimits a cavity for receiving at least a part of the patient body, with at least two or three open sides, the open sides providing access to the cavity. The open or closed annular magnet structure being disposed with the axis of the open or closed annular shape oriented with at least one vertical directional component and devices being provided for vertical translation of the magnet structure or the patient relative to the magnet structure.