Consensus regarding diagnosis and management of osteoporosis in premenopausal women (PW) is still lacking, due to few studies carried out in this population.ECTS and IOF convened a working group to produce an updated review of literature published after 2017 on this topic.Fragility fractures in PW are rare and mostly due to secondary osteoporosis, i.e. in presence of an underlying disease such as hormonal, inflammatory or digestive disorders. In absence of another disorder, low bone density (BMD) together with fragility fractures qualifies as "idiopathic osteoporosis". In contrast, low BMD alone does not necessarily represent osteoporosis in absence of bone microarchitectural abnormalities.BMD increases in PW with osteoporosis when the underlying disease is treated. For example, in celiac disease, an increase of 9% in radius trabecular volumetric density was achieved after 1 year of gluten-free diet, while anti-TNF alfa improved BMD in PW with inflammatory bowel diseases. In amenorrhea, including anorexia nervosa, appropriately delivered estrogen replacement therapy can also improve BMD. Alternatively, antiresorptive or anabolic therapy has been shown to improve BMD in a variety of conditions, the range of improvement (3-16%) depending on skeletal site and the nature of the secondary cause. No studies were powered to demonstrate fracture reduction. The effects of bisphosphonates in childbearing women have been scantly studied and caution is needed.The majority of PW with osteoporosis have an underlying disease. Specific therapy of these diseases, as well as antiresorptive and anabolic drugs, improve BMD, but without evidence of fracture reduction.