The aim of this study was to determine whether the results of chemonucleolysis are related to the size of the disc herniation and to the dimensions of the spinal canal. Short and long-term results (average follow-up 4 and a half years) of 148 patients were evaluated. Measurements made with a divider included the size of the disc herniation related to the sagittal diameter of the spinal canal at the discal level and the transverse interligamentous diameter at the level of the facet joints. The morphology of the lateral recess was also assessed. Measurements were initially made by five observers and were repeated eight times and on eight computed tomography (CT) scans in order to assess intra- and interobserver variability. Measurements of the entire series were then made by the two observers demonstrating a good intra- and interobserver reproducibility. Of the 148 patients 74% had an overall successful result. No significant difference was disclosed when comparing the various parameters of the clinical results with the size of the herniation. Similarly, a lack of correlation was also found between the clinical results and the dimensions of the spinal canal and of the lateral recess. In this series, the results were not significantly influenced by the size of the herniation or the morphology of the spinal canal.