The purpose of this study was to examine the relationships between measurements of lumbar lordosis, pelvic tilt, and abdominal muscle performance during normal standing. In addition, the reliability of the measurements used in this study was examined. Measurements of lumbar lordosis, pelvic tilt, and abdominal muscle performance were taken of 31 healthy adults aged 20 to 33 years. Each measurement was taken twice, and the measurements were shown to be reliable. The Spearman's rho correlation of the abdominal muscle performance measurements with pelvic tilt was .18 and with lordosis was .06. The Pearson product-moment correlation of lordosis with pelvic tilt was .32. The results indicate that lumbar lordosis, pelvic tilt, and abdominal muscle function during normal standing are not related. This study demonstrates the need for a reexamination of clinical practices based on assumed relationships of abdominal muscle performance, pelvic tilt, and lordosis.