OBJECTIVE: To examine sex-related and vertebral-level-specific differences in vertebral shape and to investigate the relationships between the lumbar lordosis angle and vertebral morphology. DESIGN AND PATIENTS: Lateral thoracic and lumbar spine radiographs were obtained with a standardized protocol in 142 healthy men and 198 healthy women over 50 years old. Anterior (Ha), central (Hc) and posterior (Hp) heights of each vertebra from T4 to L4 were measured using a digitizing technique, and the Ha/Hp and Hc/Hp ratios were calculated. The lumbar lordosis angle was measured on the lateral lumbar spine radiographs. RESULTS: Ha/Hp and Hc/Hp ratios were smaller in men than women by 1.8% and 0.7%, respectively, and these ratios varied with vertebral level. Significant correlations were found between vertebral shape and the lumbar lordosis angle. CONCLUSIONS: These results demonstrate that vertebral shape varies significantly with sex, vertebral level and lumbar lordosis angle. Awareness of these relationships may help prevent misdiagnosis in clinical vertebral morphometry.