Objective To investigate incidence and onset of deep vein thrombosis (DVT) in elderly patients with hip fracture, and to evaluate the laboratory tests of plasma levels of D-Dimer, fibrinogen(FIB)and platelet(PLT) in diagnosing DVT. Methods From January, 2005 to December, 2006, 112 patients, 47 men and 65 women, aged 65 and over, were recruited into this study. Their mean age was 75.5 (range, 65 to 90) years. D-Dimer, FIB and PLT, as high specific fibrin degradation products, were detected via laboratory testing. The incidence, onset and distribution of DVT in these cases were observed. Univariate analysis was used to determine the associations between laboratory values and DVT. Influences of sex and type of hip fracture on the concentration of D-Dimer were studied as well. Results DVT was detected in 18 patients by means of B-mode ultrasonography and venography. The incidence rate of DVT in the elderly was 16. 1%. The onset of DVT took place between the second day and sixth day of hospitalization (average, 5.4 days), apparently earlier than the time of surgery (11. 6 days). Serum D-Dimer level was found significantly higher in the DVT group (P ＜ 0. 05) whereas levels of plasma FIB and PLT showed no significant influence on DVT(P ＞ 0. 05) . The D-Dirmer level was strongly influenced by type of fracture but not by sex.Conclusions Elderly patients with hip fracture have a high incidence of DVT. Since the onset of DVT usually happens before surgery, emergent operation is strongly indicated. A normal level of serum D-Dimer may be clinically significant in excluding the onset of DWT, but a simple rise in plasma D-Dimer level may not indicate DWT. The plasma levels of FIB and PLT may have no clinical significance in diagnosing DVT.D-Dimer level is not associated with sex of patients but with type of fracture.