PURPOSE: The purpose of this study was to evaluate the relationship between osteoporosis and skin thicknessas shown by CT scanning. MATERIALS AND METHODS: Eighty- six women with osteoporosis (mean age, 52) and 51 normalcontrols (mean age, 50) participated in the study. For a quantitative CT examinations, a CT scanner(Somatom Plus,Siemens) was used. Osteoporosis was defined as present when spinal bone mineral density was more than 2.5 standarddeviations below young normal density, as determined by quantitative CT. Patients with endocrinologic, malignantor collagen disease and undergoing antimetabolite or steroid therapy were excluded. The thickness of back skin wasretrospectively measured at the third lumbar vertebra level, as seen on CT films, using a conventional magnifier.For statistical analysis, Students' t test and Spearman's rank correlation were used. RESULTS: On the basis of CTscans, the mean thickness of back skin in the osteoporotic group(0.50+/-0.20 mm) was significantly less than innormal control subjects(0.80+/-0.23 mm) (p<0.001). Significant correlation was observed between skin thickness andbone mineral density(r=0.523, p<0.0001). Sensitivity, specificity, accuracy, and positive and negative predictivevalues were measured as 76, 78, 76, 88, 62% with a cut-off value of 0.6 and 84, 61, 77, 81, 66% with a cut-offvalue of 0.7, respectively. CONCLUSION: The present study demonstrated that the thickness of back skin, asmeasured by CT scanning, is predictive of osteoporosis.