BACKGROUND: Deep vein thrombosis (DVT) of the lower limbs is one of the severe complications of total hip replacement (THR)during the perioperative period. The incidence rate was high. The effect of primary disease on the DVT after THR in the elderly remains poorly understood.OBJECTIVE: To explore the effect of primary disease on DVT after THR in the elderly.METHODS: 147 cases with unilateral THR aged 64-93 years, were included and divided into two groups. Fracture group contained 68 cases, which of them were all traumatic femoral neck fracture ones. Osteopathia group contained 79 cases, and they had no traumatic injury. We selected total hip prostheses according to their physiological age, preoperative socialization ability,substantia ossea and life expectancy. Biological prosthesis in 5 cases and mixed prosthesis in 12 cases were used, while the others used bone cement prosthesis. If the patient had pain and/or swelling on the injured limb, with or without Homans/Neuhofs sign, we did the pressurized ultrasonic Doppler to examine whether the patient had got DVT.RESULTS AND CONCLUSION: In the fracture group, 32 cases had swelling in the injured limbs, and 20 cases with pain, 15 cases with Homans/Neuhofs sign, and 29 DVT cases were confirmed by the pressurized ultrasonic Doppler. One femoral neck fracture case of THR had no DVT clinical signs and was dead 17 days later. The autopsy found that it was an mixed type combined of pulmonary embolism; Osteopathia group: 20 cases had swelling in the injured limbs, and 11 cases of pain, 9 cases of Homans/Neuhofs sign, 20 DVT cases were confirmed by the pressurized ultrasonic Doppler. The blood coagulation state was greater, and the incidence rate of DVT in the lower limbs was greater in the fracture group compared with osteopathia group (P ＜ 0.05). These indicated that femoral neck fracture is a high risk factor for DVT development in lower limb affer THR in the elderly.