We report a quite rare case of acquired type 3-like von Willebrand syndrome (vWS) that preceded full-blown systemic lupus erythematosus (SLE). A 16-year-old woman with no previous disease history and no family history of hemorrhagic diathesis was referred to our hospital because of recurrent epistaxis and gingival bleeding. She was diagnosed as having atypical type 3 von Willebrand disease because of prolonged bleeding time with normal platelet count and prolonged activated partial thromboplastin time (aPTT), and an almost complete absence of von Willebrand factor (vWF) antigen, ristocetin cofactor activity (vWF:RCo) and ristocetin-induced platelet agglutination (RIPA). Furthermore, electrophoretic analysis of plasma vWF revealed a trace amount of vWF and an absence of the multimeric form of vWF. Infusions of either vasopressin or factor VIII/vWF concentrates improved bleeding symptoms and corrected the aPTT and RIPA. However, she complained of low-grade fever, general fatigue and polyarthralgia 5 months later, and leukocytepenia and hypo-complementemia developed. Anti-double-stranded DNA antibodies and lupus erythematosus cells became positive. These findings were compatible with SLE. Mixing the patient's platelet-poor plasma (PPP) with normal platelet-rich plasma (PRP) (PPP/PRP = 2/1) resulted in a complete inhibition of RIPA, suggesting the presence of vWF inhibitor in her plasma. Treatment with prednisolone (40 mg/day) started and the bleeding tendency gradually improved. One month later, all of the laboratory data including aPTT, bleeding time, RIPA and vWF:RCo became normal. These findings indicate that she has an acquired type 3-like vWS associated with SLE.