Purpose <p>Sperm progressive motility (PR) is correlated with the sperm DNA fragmentation index (SDF). Moreover, abnormalities in sperm tails are closely associated with the quality of sperm PR. However, the correlation of abnormal sperm tails with the SDF remains unknown.</p> Methods <p>Routine semen examination was performed according to the World Health Organization guidelines with a computer-assisted semen analysis system. SDF analysis was conducted via the sperm chromatin structure assay method. Spearman correlation was used to test the correlation of the SDF with age and conventional semen parameters. The relationship between the SDF and abnormal tails was explored by binary logistic regression analysis, restricted cubic spline (RCS) analyses and subgroup analysis. ROC curves were used to assess the predictive capacity of age, abnormal tails and PR for the SDF.</p> Results <p>The SDF was associated with sperm morphology, with a significant correlation observed with abnormal sperm tails (r = 0.491, <i>P</i> &lt; 0.001). Binary regression analysis revealed that abnormal sperm tails were an independent influencing factor of the SDF. RCS analyses and Trend analysis suggested that as the number of abnormal sperm tails increased, the risk of an abnormal SDF also increased, and the trend was statistically significant (<i>P</i> for trend &lt; 0.001). The ROC curve demonstrated that abnormal sperm tails had good discriminatory ability for the SDF (AUC: 0.757, <i>P</i> &lt; 0.001).</p> Conclusion <p>Abnormal sperm tails are an independent influencing factor of the SDF, and a higher number of abnormal tails is associated with an increased risk of an abnormal SDF.</p>