To compare diffusion tensor imaging (DTI) parameters of the spinal cord between patients with cervical spondylotic myelopathy (CSM) and normal subjects, and investigate their significance in the clinical diagnosis, surgical planning and post-operative evaluation of CSM. Routine sequence magnetic resonance imaging (MRI) and DTI scans were performed in 50 normal subjects and 60 cases of CSM with 3.0-T MR. DTI images, apparent diffusion coefficient (ADC) and fractional anisotropy (FA) colormaps corresponding to spinal cord cross-sections were obtained. The spinal cord function of CSM patients was measured using modified Japanese Orthopaedic Association (mJOA) scoring and Nurick grade at different times. The changes in DTI parameters and their correlation with spinal cord function scores were analysed by SPSS 19. There were significant differences in DTI parameters of the spinal cord between normal subjects and patients with CSM (ADC: 1.119 ± 0.087 vs. 1.395 ± 0.091, P < 0.01; FA: 0.661 ± 0.057 vs. 0.420 ± 0.080, P < 0.01). The FA values at the maximal compression level of the spinal cord in the patients with CSM were significantly associated with the mJOA score pre-operatively, 1 week, and 1, 3 and 6 months post-operatively, with Pearson's correlation coefficients of 0.58 (P < 0.01), 0.53 (P < 0.05), and 0.51 (P < 0.05), 0.54 (P < 0.05) and 0.55 (P < 0.05), respectively. However, the FA values were significantly negatively associated with the Nurick grade, with Pearson's correlation coefficients of - 0.40 (P < 0.05), - 0.39 (P < 0.05), and -0.41 (P < 0.05), - 0.45 (P < 0.05) and - 0.44 (P < 0.05), respectively. DTI may play a significant role in diagnosing and predicting the development of CSM. These slides can be retrieved under Electronic Supplementary Material.