A patient with systemic lupus erythematosus (lupus) is described, in whom stress fractures of both legs developed, accompanied by swelling of both ankles. The swelling of the right ankle associated with fracture mimicked lupus synovitis, but resolved with healing of the fracture. On the left side the swelling represented true lupus synovitis coexistent with the tibial stress fracture. This presentation posed a diagnostic dilemma. It is necessary to maintain vigilance in the diagnosis of these fractures in lupus.