The aim of this study was to determine how polymorphisms of transporters associated with transporter and antigen processing 1 (TAP1) alleles contributed to the pathogenesis of systemic lupus erythematosus (SLE) in Taiwan. We collected 88 patients with SLE and 104 healthy people for the control group. The polymorphisms were detected as a result of polymerase chain reaction (PCR)-based restriction analysis. Associations between SLE and TAP1 polymorphisms were evaluated. The results revealed no significant differences between the healthy individuals and SLE patients with TAP1-1 (Dpn II) and TAP1-2 (Acc I) polymorphisms ( P=0.10 and 0.36, respectively). However, the G alleles of TAP1-1 and TAP1-2 were significantly more common than the A alleles in serositis of SLE patients (chi(2)=11.16 and P=0.004, chi(2)=8.10 and P=0.02, respectively).