Aims: The relationship between lumbar spine angles and back pain has been considered from past. Little study has been performed on evaluation of all lumbar angles including sacral inclination, lumbosacral, sacral horizontal, lumbar lordosis and segmental lumbar lordosis angles in patients with acute and chronic back pain and normal individuals. The aim of this study was evaluating these angles in the three mentioned groups.Materials & Methods: This case-control study was performed on back pain patients who referred to the physical medicine clinic of one of Tehran’s hospitals in 2010. Subjects were selected by convenience sampling method and were divided into three normal, acute and chronic back pain groups that each consisted of 35 members. Subjects’ demographic data, history and physical examination were recorded in questionnaires and their height, weight, abdominal circumference and BMI were measured. Radiographic clichés were investigated by a specialist and lumbar angles were recorded. Data was analyzed by ANOVA, independent t-test and Pearson correlation coefficient using SPSS 18 software.Results: The mean range of sacral inclination angle was 42.40±9.18 that the difference was not significant in two genders, but was significant in acute and chronic patients and normal individuals. There was no statistical difference regarding other angles among patients and normal individuals.Conclusion: The degree of sacral inclination angle is significantly higher in back pain patients compared to normal people. Paying attention to this angle in patients’ radiographic clichés is of importance and its correction may be beneficial in reducing their symptoms.