Objective. To analyze the method for assessing a degree of spinal canal narrowing based on anatomical aspects of lumbar spinal stenosis. Material and Methods. Twenty two patients with 41 stenotic segments were involved in the study. Mean age of patients was 51.8 years. Mean number of stenotic segments in one patient was 2.1. Eight radiological criteria were measured in all patients. Measurements were carried out at the level of the middle of intervertebral disc and facet joints. The linear pair correlation was calculated for all criteria. The regression equations were composed based on correlation coefficients. Results. Strong linear correlation between the linear and area variables was found. The analysis of regression equations showed the adequacy of mathematical models and high value of the multiple correlation coefficient. To describe a degree of spinal canal narrowing the authors suggested using a stenosis coefficient as the ratio of the sum of lateral canal areas to the dural sac cross-sectional area.Comparison between average values of this coefficient in the study and the control groups showed statistically significant differences. Conclusion. The new approach to searching for an optimal radiological criteria of spinal canal narrowing is used. Based on the obtained data, the parameter "stenosis coefficient" is introduced, which has high correlation with the numerical grading scales. Results obtained in the small sample are encouraging.