Pleuropulmonary complications of systemic lupus erythematosus (SLE) occur in 50-70% of patients and include pleuritis, pleural effusions, acute lupus pneumonitis, diffuse interstitial lung disease, atelectasis, diaphragmatic dysfunction and bronchiolitis obliterans. Additionally, a syndrome of acute reversible hypoxemia has recently been documented. This seems to occur in patients hospitalized for exacerbations of SLE and may be due to pulmonary leukoaggregation. It has become clear that other groups of pulmonary complications may be specifically associated with the antiphospholipid antibodies, both in patients with SLE and in those suffering from the "primary" antiphospholipid syndrome. These include pulmonary embolism and infarction, both thromboembolic and perhaps nonthromboembolic pulmonary hypertension, pulmonary arterial thrombosis, pulmonary microthrombosis, adult respiratory distress syndrome, intraalveolar pulmonary hemorrhage, as well as a postpartum syndrome.