Objective To investigate the effect of femoral offset reconstruction on pelvic stabil ity during gait after total hip arthroplasty. Methods According to the inclusion criteria, 29 patients undergoing unilateral total hip arthroplasty between January 2000 and December 2005 were selected. There were 10 males and 19 females with an average age of 64.3 years (range, 33-75 years). The affected hips included 15 left hips and 14 right hips. The follow-up time was from 5 to 10 years (mean, 7.7 years). The Harris score was 90 to 100 (mean, 97) at last follow-up. The femoral offset ratio (FOR) was calculated by measuring the femoral offset of the bilateral hips on radiograph, and then the patients were divided into 2 groups: group A (the femoral offset of diseased hip was less than that of normal hip, n=10) and group B (the femoral offset of diseased hip was greater than that of normal hip, n=19). The pelvis kinematic variables were measured by three-dimensional gait analysis to collect the magnitude of pelvic obl ique angle (POA). Results In group A, the FOR was 0.81 ± 0.08 and the POA was (—0.42 ± 0.91)°. In group B, the FOR was 1.27 ± 0.15 and the POA was (1.02 ± 0.94)°. For the normal hip, the POA was (1.15 ± 0.85)°. The POA was significantly less in group A than in group B and the normal l imb (P lt; 0.05). The difference in POA had no significance between group B and the normal hip (P gt; 0.05). The POA was positive relative with FOR (r=0.534, P=0.003), and the regression equation was y= — 2.551+ 2.781x. Conclusion The femoral offset reconstruction is crucial to improve hip abductor function and gait.