In the last years it has been recognized that patients with systemic lupus erythematosus (SLE) are at high risk of osteoporosis (OP) and fractures, both occurring through disease-specific (chronic arthritis, reduced physical activity, induction of cytokines promoting bone resorption, renal impairment, endocrine factors) and nondisease-specific mechanisms (sunshine avoidance with consequent vitamin D deficiency, glucocorticoids, immunosuppressants and chronic anticoagulants). Regarding anticoagulants, subcutaneous heparin is crucial against the risk of recurrent thromboembolism or pregnancy loss, specifically in patients with SLE and anti-phospholipid syndrome (APS). Thus heparin-induced OP represents one of the hazards of this treatment, first because heparin must be used long-term and secondly because pregnancy and lactation themselves may predispose to OP and fractures. Current data suggest the use of prophylaxis with calcium and vitamin D in all patients treated with heparin during pregnancy. Nevertheless glucocorticoid-induced OP (GIOP) is considered the most serious risk factor for OP and fractures in SLE patients. All guidelines recommend general measures and supplementation with calcium and vitamin D in all patients. However when considering premenopausal patients, there is no generally recommended treatment. Bisphosphonates, which are considered the first choice therapy for the prevention and treatment of GIOP, should be used 'cautiously' in these patients. Therefore the potential risks and lack of efficacy data on fracture risk reduction in premenopausal patients must be weighed against their proven efficacy in postmenopausal patients.