A comparison was made of the densitometric values of the lumbar vertebrae obtained using quantitative Computed Tomography, and those measured with dual energy X-ray absorptiometry. A selected group of patients at increased risk of developing postmenopausal osteoporosis was chosen: women who had undergone bilateral oophorectomy in child-bearing years. The densitometric data recorded revealed a considerable decrease in bone mass, in particular in the cancellous portion of the vertebrae (a 17% change in the quantitative Computed Tomography value and a 13% decrease in that of dual energy X-ray absorptiometry a one year after oophorectomy). Although quantitative Computed Tomography and dual energy X-ray absorptiometry demonstrated a similar trend in bone mass reduction, given the marked and unexplained variability of both absolute values and percent variations, it was impossible to establish a clinically useful mathematical correlation between the two sets of data. Quantitative Computed Tomography is the densitometric procedure of choice to study metabolic bone disorders that involve mainly tha cancellous portion, such as postmenopausal osteoporosis. Nevertheless, given its accuracy, short execution time, lower radiation dose required, as well as good sensitivity in the measurement of bone mass variations, it would seem that dual energy X-ray absorptiometry could also find a place in clinical studies on postmenopausal osteoporosis.