Thrombotic microangiopathy (TMA) is a well-recognised complication following transplantation, often due to an underlying genetic predisposition, medications or rejection. The use of eculizumab in these settings has been previously described, but its role still remains to be clarified. A 45-year-old man, with a history of type 1 diabetes mellitus and subsequent end-stage kidney failure, presented for a simultaneous pancreas-kidney transplant. Immunologically, he was well matched with the donor, and he received standard induction immunosuppression including tacrolimus. His early transplant course was complicated by Haemophilus parainfluenzae paronychia and a Pseudomonas aeruginosa catheter-associated urinary tract infection. Within 1 week, he developed thrombotic microangiopathy with significant renal dysfunction and eventual dialysis dependence, without evidence of transplant rejection on biopsy. He was also noted to have antiphospholipid antibodies in moderate titres. The TMA did not resolve despite cessation of tacrolimus, and he was subsequently commenced on eculizumab. The patient achieved a partial remission from TMA, with ongoing biochemical evidence of haemolysis, although now with stable graft function, despite significant damage. His transplanted pancreas remained seemingly unaffected by TMA, and continues to function well. This case describes an unusual presentation of TMA post-transplantation and is the only described case of eculizumab use following pancreas-kidney transplant. It remains unclear in this case what the likely precipitant for TMA was, although it seems to be, at least in part, controlled by ongoing use of eculizumab, presumably by terminal complement inhibition.