Precapillary pulmonary hypertension was diagnosed in a 29 year old woman who became progressively more breathless (NYHA Class III) after her pregnancy, two years previously: systolic pulmonary artery pressure was 120 mmHg with an arterio-capillary pressure gradient of 30 mmHg. She had anti-nuclear autoantibodies detectable at 1/1000 and anti-DNA autoantibodies at 1/800 without any other manifestation of lupus. Treatment with prednisone (2 mg/kg/day) resulted in regression of her dyspnoea with a decrease of systolic pulmonary artery pressure to 65 mmHg, and of the arterio-capillary gradient to 15 mmHg; the lupus serology became negative with a clinical follow-up of 37 months. This observation shows that systemic lupus erythematosus may present with precapillary pulmonary hypertension, the conventional treatment of which may be successfully completed by steroid therapy.