The symptomatic joint disease secondary to avascular necrosis of bone (ANB) in 31 of 375 (8 per cent) patients with systemic lupus erythematosus (SLE) was characterized by polyarticular (90 per cent) and symmetric (83 per cent) involvement. Progressive deterioration requiring orthopedic intervention occurred in 11 (35 per cent) patients. No distinguishing clinical or treatment differences were found comparing patients with symptomatic ANB and selected cortico-steroid-treated, asymptomatic, control subjects with SLE. Complete roentgenographic surveys revealed symmetric, polyarticular abnormalities of subchondral and cortical bone consistent with ANB in eight of 31 (26 per cent) of the control subjects. A positive correlation was found between roentgenographic ANB and disease treatment with high doses of corticosteroids. The study suggests that ANB may be present in excess of 30 per cent of the patients with SLE and is most often subclinical, asymptomatic and nonprogressive.