We herein describe for the first case of simultaneous liver and kidney transplantation (SLK) in an HCV/HIV-coinfected patient with severe hemophilia in Japan. The patient was a 61-year-old Japanese man with HCV cirrhosis. He was diagnosed with haemophilia B at age 1 year. He was infected with HCV and HIV due to imported contaminated blood products. The patient's liver disease was classified as Child-Pugh C, Model for End-Stage Liver Disease score 38. He had been on hemodialysis for 6 years, but both HIV RNA and HCV RNA had been undetectable after appropriate antiviral therapies. In September 2019, the patient underwent successful SLK. The donor was a man in 60’s deceased due to cerebral hemorrhage. Regular DDLT was performed using the piggyback technique with a full-sized liver graft. Cold ischemia time was 566 min, and the graft liver weighed 1,154 g. The graft kidney was transplanted extraperitoneally in the right iliac fossa. A total of 76 U of packed red cells and 100 U of fresh frozen plasma were infused during the 12-h procedure, which required packing and subsequent depaking procedure on day3. Also, the administration of clotting factor IX discontinued on day 3. The immunosuppressive regimen was based on i.v. induction with 2 mg/kg of basiliximab and 1g methylprednisolone and subsequent oral administration of mycophenolate mofetil and prednisolone, followed by low dose taclorimus after 1w for kidney sparing purpose. Steroid therapy was gradually discontinued at 3 months after SLK. The same pretransplantation antiretroviral therapy (ART; tenofovir and doltegravir) was introduced after 3 days when the CD4 cell count was more than 300/μl and HIV-RNA was within undetectable range. The postoperative course was uneventful without infectious complication, and the patient was transferred to referral hospital on day 90 and discharged home on day 111. Herein, we report the first case of SLK for HIV/HCV co-infected hemophilic patient in Japan. Strategic surgical planning and meticulous pre and post-transplant management of ART and clotting factors could lead to the success of SLK.