Osteonecrosis (ON) or avascular necrosis of bone is a well recognised complication in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The pathogenesis of ON is probably multifactorial, of which abnormal hemostatic state such as the presence of antiphospholipid antibodies (aPL) may play an important role. In patients with aPL, bilateral involvement of femoral head is often found, but some patients follow an asymptomatic course. Atypical site ON (talus, vertebral, carpal lunate) and/or multiple ON (more than three bones affected) are not uncommon in patients with APS. HIV patients positive for aPL had also a higher risk for the development of ON. By definition, frank and sustained arthritis are not usually seen in patients with Primary APS. On the other hand, arthralgias are not uncommon. Other anecdotal features such as stress fractures have been reported to be associated with aPL. The management of patient with aPL and ON without venous or arterial thrombosis is still controversial. A high diagnostic suspicion is crucial in order to prevent the onset of ON in new territories and to avoid the need of joint replacement.