Objective We aimed to evaluate the application value of diffusion-weighted imaging (DWI) for assessing paradoxical puborectalis syndrome (PPS) in patients with obstructive defecation syndrome (ODS). Methods The medical records of 51 ODS patients who underwent magnetic resonance (MR)-DWI and MR-defecography were retrospectively reviewed. The differences in the apparent diffusion coefficient (ADC) and the thickness in the right and left branches, including the absolute minus value, of the puborectalis muscle between the PPS(+) and PPS(-) groups were compared. Results The difference in the absolute minus value of the ADC in the right and left branches between the two groups was statistically significant (0.10±0.08 vs 0.20±0.16, P=0.029), and PPS(+) patients had a lower minus value than did PPS(-) patients. However, there was no statistically significant difference in the ADC value between the two groups. Similarly, no statistically significant differences were found in either the thickness or the absolute minus value of the thickness between the two groups. Conclusion DWI may have value in quantitatively assessing the puborectalis muscle in ODS patients,while the role of puborectalis thickness needs further study.