Horseshoe kidney is a fusion anomaly found in approximately one in 400–600 people. Due to vascular and ureteral variations, transplantation with a horseshoe kidney presents a technical challenge. In our case, the isthmus connected the upper poles and contained parenchyma. It consisted of three renal arteries, five veins collected to the inferior vena cava, and two ureters and pyelons. It was implanted en bloc to the left side retroperitoneally. During the early period, cellular and humoral rejection was confirmed and treated. For a urine leak, double J catheters were implanted into both ureters. Later, the first catheter was removed. Subsequently, urinary sepsis developed, necessitating graftectomy. The uncommon anatomy of ureters and antibody-mediated rejection (AMR) may both be factors for a ureter tip necrosis led to an infected urinoma. After other Hungarian authors, we also report a horseshoe kidney transplantation that was technically successful. However, after an adequately treated but severe acute humoral rejection, the patient developed sepsis, and the kidney had to be removed. We conclude that transplantation with horseshoe kidney is technically feasible but may increase the risk for urinary complications and resultant infections. Careful consideration of risk and benefit is advised when a transplant professional is faced with this option.