The purpose of the study was to determine whether a relationship existed between the magnitude of thoracic kyphosis in women with osteoporosis or osteopenia and their Functional Reach (FR) test scores, lower-extremity active joint ranges of motion (AROM), and lower-extremity muscle length. Sixteen women with diagnoses of osteoporosis or osteopenia between the ages of 49 and 81 referred to outpatient physical therapy volunteered for the study. Tests were performed and measurements obtained during the initial physical therapy examination. The magnitude of thoracic kyphosis was measured with a flexicurve and expressed as the kyphosis index (KI). Lower-extremity AROM and muscle length were measured with a universal goniometer. The Spearman rank correlation coefficients were computed between KI and FR scores, KI and AROM of the lower extremities, and KI and muscle length of the lower extremities. Statistically significant negative correlations existed between KI and FR (r = −0.60, P < .01); KI and left plantar flexion AROM (r = −0.52, P < .05); KI and right knee flexion AROM (r = −0.44, P < .05); KI and left rectus femoris length (r = −0.55, P < .05); KI and right hamstring length (r = −0.62, P < .01); and KI and right gastrocnemius length (r = −0.66, P < .01). There were statistically significant relationships between the magnitude of thoracic kyphosis in women with osteoporosis or osteopenia and their FR test scores, and lower-extremity AROM and muscle length. Physical therapists treating women diagnosed with osteoporosis and osteopenia with the postural impairment of increased thoracic kyphosis should incorporate interventions to improve lower-extremity AROM and muscle length.