Objective To study the effect of simultaneous bilateral total hip arthroplasty in a single procedure. Methods From October 1999 to March 2004, 15 patients (30 hips) underwent simultaneous sequential bilateral total hip arthroplasty (THAs) in a single procedure. Of the 15 patients, 11 were male (22 hips) and 4 were female (8 hips). Their ages ranged from 35 to 70 years. Their courses of disease ranged from 1 year to 50 years (4.8 years on average). The Harris scores of the joint function before the operation ranged from 12 to 45 points (27 points on average). Five were done with Smith-Peterson and 10 were done with Moore. Results The operative time was 3 hours and 25 minutes to 5 hours (4 hours and 10 minutes on average). The volume of blood transfusion during operation was 400 to 2 400 ml (1 160 mlon average). All the 15 patients were followed up for 3 to 35 months (18 monthson average). The Harris scores of the joint function after the operation rangedfrom 70 to 100 points (86 points on average). There was significant difference in the scores between before and after operations (Plt;0.05). There was only 1death within 1 months of the operation and no serious between complications such as infection, pulmonary embolism, and deep vein plug. All the patients were still ambulant in the community and gained significant pain relief. Conclusion Simultaneous bilateral total hip arthroplasty in a single procedure is a safe and effective method. However, the decision of performing singlestage bilateral total hip arthroplasty should be carefully made and preoperative preparation should be sufficiently made.