Purpose <p>Spastic paraplegia type 5 (SPG5) is a rare neurodegenerative disease diagnosed primarily through genetic testing.We identified a specific spinal cord sign on conventional MR imaging to help narrow the scope of genetic screening.</p> Methods <p>In 25 patients with SPG5 and 21 healthy controls (HCs), the spinal cord cross sign was evaluated on T2*-weighted imaging. The morphological and signal characteristics of the dorsal column (DC), ventral funiculi (VF), dorsal horn (DH), ventral horn (VH), and intermediate zone (IMZ) were assessed. Differences in fractional anisotropy (FA) values within specific regions between HC and SPG5 were tested using Student’s t-test. Spearman correlation was used to evaluate associations between cross-sign scores, FA values, and clinical indicators.</p> Results <p>The cross sign was detected in the cervical spinal cord of all SPG5 patients. The occurrence of T2 hyperintensity in the DC, VF and IMZ was 100%,100% and 88%,respectively. Bilateral VH morphology was normal in 14.4% of cases, blurred in 49.6%, and absent in 36%.Bilateral DH morphology was normal in 13.6%, blurred in 56%, and absent in 30.4%. FA values were reduced in these spinal cord regions. Cross-sign scores were negatively correlated with FA values in both grey (<i>r</i> = -0.70~-0.37) and white matter (<i>r</i> = -0.78~-0.70). Cross-sign scores were positively correlated with Spastic Paraplegia Rating Scale (<i>r</i> = 0.57) and disease duration (<i>r</i> = 0.42).</p> Conclusion <p>The spinal cord cross sign was a potential imaging marker for SPG5. Cross-sign scores were associated with disease duration and severity in SPG5 patients.</p> Trial registration <p>A Registered Cohort Study on Spastic Paraplegia,NCT04006418&#xa0;Registered 1 July 2019, <a href="https://clinicaltrials.gov/study/NCT04006418">https://clinicaltrials.gov/study/NCT04006418</a>.</p>