We designed and built a non-invasive instrument, called Vertebral Metrics, to measure the x, y, and z positions of each spinous process of the spine on a standing position. In the present study, we perform a comparative evaluation of Vertebral Metrics, by comparing the results obtained from this instrument with those from a validated optoelectronic system of stereophotogrammetry, with 10 infrared cameras. The sample was composed of 11 women aged between 14 and 39 years. After marking the various points on the spinal column, from the first cervical vertebra to the first sacral vertebra, they were measured first with the new instrument (Vertebral Metrics) and then by means of the optoelectronics system. Afterwards, the results were subjected to a thorough comparison. The statistical comparison of the results was performed using an ANOVA model with three factors (Instrument, Subject, and Vertebra) for the intervertebral distance.