Systemic lupus erythematosus (SLE) is often complicated by pericarditis with effusion, which generally responds well to glucocorticoid. We report herein a Japanese patient with SLE who showed a sign of cardiac tamponade and severe chest and back pain because of massive intractable pericardial effusion. Pulse glucocorticoid and pulse cyclophosphamide gained marginal effects. Pericardial effusion accumulated again soon after ultrasound-guided pericardiocentesis and drainage. Pericardial fenestration performed surgically as a last resort, for draining pericardial fluid into the pleural space, was very effective, and only a much smaller amount of fluid was observed in the space thereafter in comparison with the volume before the surgery. Pathological examination of the retrieved pericardium unfolded intense hyperplasia of small vessels and capillaries. Levels of IL-6 and TNF-alpha in pericardial effusion were extremely higher than those in serum. Pericardial effusion with extensive capillary hyperplasia in SLE would be resistant to medical treatment and require surgical fenestration.