Objective: The exact volume of the vertebral body is necessary for the evaluation, treatment and surgical application of related vertebral body. Thereby, the volume changes of the vertebral body are monitored, such as infectious diseases of vertebra and traumatic or non-traumatic fractures and deformities of the spine. Several studies have been conducted for the assessment of the vertebral body size based on the evaluation of the different criteria of the spine using different techniques. However, we have not found any detailed study in the literature describing the combination of the Cavalieri principle and vertebral body volume estimation. Materials and methods: In the present study we describe a rapid, simple, accurate and practical technique for estimating the volume of vertebral body. Two specimens were taken from the cadavers including ten lumbar vertebras and were scanned in axial, sagittal and coronal section planes by a computed tomography (CT) machine. The consecutive sections in 5 and 3 mm thicknesses were used to estimate the total volume of the vertebral bodies by means of the Cavalieri principle. Furthermore, to evaluate inter-observer differences the volume estimations were carried out by three performers. Results: There were no significant differences between the performers' estimates and real volumes of the vertebral bodies (P > 0.05) and also between the performers' volume estimates (P > 0.05). The section thickness and the section plains did not affect the accuracy of the estimates (P > 0.05). A high correlation was seen between the estimates of performers and the real volumes of the vertebral bodies (r = 0.881). Conclusion: We concluded that the combination of CT scanning with the Cavalieri principle is a direct and accurate technique that can be safely applied to estimate the volume of the vertebral body with the mean of 5 min and 11 s workload per vertebra. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.