Clinical consequences of osteoporotic vertebral fractures, such as back pain, functional limitations, and impairment of mood, are often cited as justification for prevention and therapy. But these symptoms are poorly characterized, and a clinical grading system is not available. The aim of this study was to compare clinical measures for spinal deformation and quality of life components between patients with osteoporosis and patients with chronic low back pain (CLBP) and to determine the relationship between spinal deformation and quality of life components. A total of 130 female patients (63 osteoporotic patients, 65 ± 7.9 years, and 77 CLBP patients, 56 ± 6.5 years) had a standardized interview on quality of life components (pain, activities of daily life, mood) and clinical measures of spinal deformation (height reduction [HR], distance from occiput to wall [DOW], and distance from iliac crest to ribs [DIR]). Spinal X-rays were reviewed in all patients for the evidence of vertebral fractures. In osteoporotic patients, vertebral deformity was quantified by the spine deformity index (SDI) on X-rays. It was assessed whether subgroups could be identified by a combination of indices for spinal deformation (SDI, HR, DOW) using a cluster analysis. Back pain was a major complaint in both groups, without differences in pain intensity and frequency. Impairment of general well being and mood was found in about one-third of the patients in both groups. Independent of age, the disability score was significantly higher in patients with osteoporosis than in patients with CLBP. Both groups differed with respect to clinical measures of spinal deformity (HR, DOW, DIR). Among osteoporotic patients, parameters of quality of life were not linearly related to the degree of radiologically assessed vertebral deformity, but osteoporotic patients with two or more vertebral fractures tended to have more functional limitations than those with only one fracture. There was, however, a significant linear relationship between components of quality of life (disability score, pain) and clinical measures of spinal deformation (HR, DOW, DIR). The osteoporotic patients were subdivided into three clusters. The first group was characterized by low spinal deformation (↓SDI, ↓HR, ↓DOW) and little impairment of quality of life. The second group had significantly greater spinal deformation (↑SDI, ↑HR, ↑DOW) and significantly more pain and functional limitations. The third group was characterized by increased kyphosis, mainly caused by nonskeletal dysfunction (↓SDI, ↓HR, ↑DOW), but pain and functional limitations were impaired to the same degree as in the second group with severe skeletal spinal deformation. We conclude that with respect to quality of life components, functional limitation is the most specific to spinal osteoporosis and is related to clinical measures of spinal deformation. Furthermore, spinal deformation and the clinical course of osteoporosis appears to be insufficiently reflected by radiological indices of vertebral deformity (such as SDI) alone. For grading the disease and for therapeutical concepts, radiological measures and clinical evaluation should be considered in combination.