The study examined the relationship between blood transfusions during hip and knee replacement surgeries and patient complications. The analysis included 323,669 cases of total hip arthroplasty (THA) and total knee arthroplasty (TKA) from January 2019 to September 2024, comparing 2,040 pairs of patients who received a transfusion and who did not. Perioperative blood transfusion occurred in 0.63% of patients (2041 cases). Patients who received a transfusion had a significantly higher risk of complications within 30 days after surgery: the risk of further transfusion was 9.67 times higher, infectious complications 3.82 times higher, sepsis 2.30 times higher, and deep vein thrombosis was also increased. Thirty-day mortality was 2.90 times higher in patients with perioperative transfusion. The study concluded that blood transfusions in these operations are associated with an increased risk of postoperative complications and death, highlighting the need to implement strategies to conserve and manage the patient's blood.