Background Context Assessment of posture and lumbo-pelvic alignment is often a main focus in the classification and treatment of patients with low back pain. However, little is known regarding the effects of motor control interventions on objective measures of lumbo-pelvic alignment. Purpose The primary aim of this study was to describe the variation of sagittal lumbo-pelvic alignment in patients with nociceptive mechanical low back pain. The secondary aim was to compare the effects of a high-load lifting exercise (HLL) and low-load motor control exercises (LMC) on change in lumbo-pelvic alignment with a special emphasis on patients with high and low degrees of lumbar lordosis (lu) and sacral angle (sa). Study Design This study is a secondary analysis of a randomized controlled trial evaluating the effects of HLL and LMC. Patient Sample Patients from the primary study, i.e. patients categorized with nociceptive mechanical low back pain, who agreed to participate in the radiographic examination were included (n=66). Outcome measures Lateral plain radiographic images were used to evaluate lumbo-pelvic alignment regarding lumbar lordosis and sacral angle as outcomes with posterior bend as an explanatory variable. Methods The participants were recruited to the study from two occupational health care facilities. They were randomized to either the HLL or LMC intervention group and offered 12 supervised exercise sessions. Outcome measures were collected at baseline and at the end of intervention period 2 months after baseline. Between and within group analyses of intervention groups and sub-groups based on the distribution of the baseline values for lumbar lordosis and sacral angle respectively, (LOW, MID, HIGH), were performed using both parametric and non-parametric statistics. This study was supported by two grants from Visare Norr (12000 US dollars) and Norrbotten County Council (13000 US dollars). The supporting organizations were not involved in the collection of data, analysis, interpretation or drafting of the manuscript. Results The ranges of values for the present sample for lumbar lordosis were 26.9-91.6° (M=59.0°, SD=11.5°) and for sacral angle were 18.2-72.1° (M=42.0°, SD=9.6°). There were no significant differences between the intervention groups in the percent change of either outcome measure. Neither did any outcome change significantly over time within the intervention groups. In the sub-groups, based on the distribution of respective baseline values, LOW lu showed significantly increased lumbar lordosis, whereas HIGH sa , showed significantly decreased sacral angle following intervention. Conclusions This study describes the wide distribution of values for lumbo-pelvic alignment for patients with nociceptive mechanical low back pain. Further research is needed to investigate sub-groups of other types of low back pain and contrast findings to those presented in this study. Our results also suggest that re-training of lumbo-pelvic alignment could be possible for patients with low back pain.