Leg-length inequality was measured from radiographs at the level of the vertices of the femoral heads in 247 men and women aged 35-54 years. Of these, 53 had never had any low-back problem, but they had considerable variation in leg-length inequality (mean SD, 5.5 +/- 4.1 mm; range, up to 20 mm). This group of symptom-free individuals did not differ from a group of 78 persons who had disabling low-back pain (LBP) during the previous 12 months (mean SD, 5.3 +/- 4.0 mm; range, up to 17 mm). The adjusted relative risks (odds ratios) of having LBP ever and of disabling pain during the last 12 months were 0.78 (95% confidence interval, 0.43-1.17) and 1.02 (0.68-1.38), respectively, for an increase of 5 mm in leg-length inequality. The results from this study make an association between mild leg-length inequality and LBP questionable.