A 39-year-old woman had relapsing polychondritis and Behçet's disease, which was described as mouth and genital ulcers with inflamed cartilage syndrome (MAGIC). Serologic human leukocyte antigen analysis showed A24 (9), A31 (19), B56 (22), B62 (15), Cw6, DR4, DR9. Human leukocyte antigen allele analysis revealed DRB1* 0406/0901, DQA1* 0301/0301, DQB1* 0302/0303, DPB1* 0201/0501 through determining the genotype using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Treatment with methotrexate (5 mg/week) and pentoxifylline (300 mg/d) was effective to control oral ulcers, erythema nodosum, and arthritis.