A lower limb prosthesis comprising: an attachment section, a shin section, a foot section, a knee joint pivotally connecting the attachment section and the shin section, the knee joint including a dynamically adjustable knee flexion control device for damping knee flexion, an ankle joint pivotally connecting the shin section and the foot section, a plurality of sensors (52, 53, 54, 85, 87) each arranged to generate sensor signals indicative of at least one respective kinetic or kinematic parameter of locomotion or of walking environment, and an electronic control system coupled to the sensors (52, 53, 54, 85, 87) and to the knee flexion control device in order dynamically and automatically to modify the flexion control setting of the knee joint in response to signals from the sensors (52, 53, 54, 85, 87), including from one of the said sensors (52, 53, 54, 85, 87) which is operable to generate inclination sensor signals indicative of ground inclination, wherein the arrangement of the sensors (52, 53, 54, 85, 87), the electronic control system and the knee flexion control device is such that when the inclination sensor signals indicate descent of a downward incline, the electronic control system is adapted to set the damping resistance of the knee flexion control device: to a first level during a major part of the stance phase of the gait cycle and to a second, lower level during a major part of the swing phase of the gait cycle, and wherein, during an interval including a latter part of the stance phase, the electronic control system is adapted to adjust the knee flexion control device so that the damping resistance to knee flexion is between the first and second levels. an attachment section, a shin section, a foot section, a knee joint pivotally connecting the attachment section and the shin section, the knee joint including a dynamically adjustable knee flexion control device for damping knee flexion, an ankle joint pivotally connecting the shin section and the foot section, a plurality of sensors (52, 53, 54, 85, 87) each arranged to generate sensor signals indicative of at least one respective kinetic or kinematic parameter of locomotion or of walking environment, and an electronic control system coupled to the sensors (52, 53, 54, 85, 87) and to the knee flexion control device in order dynamically and automatically to modify the flexion control setting of the knee joint in response to signals from the sensors (52, 53, 54, 85, 87), including from one of the said sensors (52, 53, 54, 85, 87) which is operable to generate inclination sensor signals indicative of ground inclination, wherein the arrangement of the sensors (52, 53, 54, 85, 87), the electronic control system and the knee flexion control device is such that when the inclination sensor signals indicate descent of a downward incline, the electronic control system is adapted to set the damping resistance of the knee flexion control device: to a first level during a major part of the stance phase of the gait cycle and to a second, lower level during a major part of the swing phase of the gait cycle, and wherein, during an interval including a latter part of the stance phase, the electronic control system is adapted to adjust the knee flexion control device so that the damping resistance to knee flexion is between the first and second levels. to a first level during a major part of the stance phase of the gait cycle and to a second, lower level during a major part of the swing phase of the gait cycle, and wherein, during an interval including a latter part of the stance phase, the electronic control system is adapted to adjust the knee flexion control device so that the damping resistance to knee flexion is between the first and second levels.