A radiographic evaluation of 100 adult volunteers over age 40 and without a history of significant spinal abnormality was done to determine indices of sagittal spinal alignment. To determine the sagittal contours of the spine in a population of adults older than previously reported in the literature and to correlate age and overall sagittal balance to other measures of segmental spinal alignment. Previous studies of sagittal alignment have focused on adolescent and young adult populations before the onset of degenerative changes that may affect sagittal alignment. Radiographic measurements were collected and subjected to statistical analysis. Mean sagittal vertical axis fell 3.2 +/- 3.2 cm behind the front of the sacrum. Total lumbar lordosis (T12-S1) averaged -64 degrees +/- 10 degrees. Lordosis increased incrementally with distal progression through the lumbar spine. Lordosis at L5-S1 and the position of the apices of the thoracic and lumbar curves were most closely correlated to sagittal vertical axis. Increasing age correlated to a more forward sagittal vertical axis with loss of distal lumbar lordosis but without an increase in thoracic or thoracolumbar kyphosis. The majority of asymptomatic individuals are able to maintain their sagittal alignment despite advancing age. Loss of distal lumbar lordosis is most responsible for sagittal imbalance in those individuals who do not maintain sagittal alignment. Spinal fusion for deformity should take into account the anticipated loss of lordosis that may occur with age.