Our objective was to determine the HLA-DPB1 allele associations of anticardiolipin (aCL) and anti-beta2GPI (a(beta)2GPI) antibodies, and of clinical manifestations of the antiphospholipid syndrome (APS), in systemic lupus erythematosus (SLE). We studied 577 European patients with SLE. aCL and a(beta)2GPI antibodies were measured by ELISA. Molecular typing of HLA-DPB1 locus was performed by polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. aCL showed positive association with -DPB1*1501 (P = 0.005, OR = 7.4), and -DPB1*2301 (P = 0.009, OR = 3.3). a(beta)2GPI showed positive association with -DPB1*0301 (P = 0.01, OR = 1.9), and -DPB1*1901 (P = 0.004, OR = 8.1). In addition, livedo reticularis was associated with -DPB1*1401, and Raynaud's phenomenon with -DPB1*2001. In conclusion, HLA-DPB1 locus may contribute to the genetic predisposition to develop antiphospholipid antibodies and clinical manifestations of the APS in patients with SLE.