Objective. The aim of this study was to determine, by plain radiography, if there is a relationship between sacralization and low back pain. Methods. Five hundred lumbosacral radiographs of low back pain patients and 500 control groups were examined. Data collection consisted of the subject's age at the time of imaging, gender, number of lumbar vertebral bodies, and bilateral height measurement of the lowest lumbar transverse process. Dysplastic transverse processes were classified according to the Castellvi radiographic classification system. The incidence of sacralization in patients and the control groups was reported, and the anomaly was compared according to the groups. Results. Of these patients groups, 106 were classified as positive for sacralization, which resulted in an incidence of 21.2%. The most common anatomical variant was Castellvi Type IA (6.8%). In the control group, 84 were classified as positive for sacralization, which resulted in an incidence of 16.8%. No statistically significant difference was found between the groups for having sacralization (P = 0.09). Discussion. The relationship between sacralization and low back pain is not clear. Because of this controversial future studies need to focus on identifying other parameters that are relevant to distinguishing lumbosacral variation, as well as corroborating the results obtained here with data from other samples.