SummaryClinical studies with progestagens indicate an antiresorptive effect on bone and suggest they stimulate bone formation. Protection against bone loss is weaker than that with oestrogen. The more oestrogen-like progestagens may have a greater protective effect. In menstruating women progestagens cause ovarian suppression which outweighs any potential benefit with respect to bone.For postmenopausal women who do not wish to experience cyclical bleeding, tibolone seems appropriate for prevention of osteoporosis.