Objective: To assess the impact of tranexamic acid on the hidden blood loss after unilateral total hip arthroplasty.Methods:Totally 40 patients who received unilateral total hip arthroplasty due to femoral neck fracture were randomly divided into two groups.Group A included 20 cases without tranexamic acid

in which the patients were just given 250 ml normal saline when the surgery started; Group B included 20 cases with tranexamic acid

and the patients in this group were given 20 mg/kg tranexamic acid with 250 ml normal saline when the surgery started.The total red blood cell loss

visible red blood cell loss and hidden red blood cell loss of the two groups were measured and the comparative analysis was conducted.Results:Results of the visible red blood losses in group A and group B were (95.43±17.72)ml and (48.84±15.04)ml

respectively; the hidden red blood loss in group A and group B were (322.37±57.69)ml and (169.89±58.50) ml

respectively.The visible and hidden red blood cell losses in group B were both significantly less than those in group A(P<0.05).Conclusion:Tranexamic acid reduces both the visible and hidden red blood loss after the unilateral total hip arthroplasty.