Objective To evaluate the significance of lactate dehydrogenase (LDH) as a predictor of in-hospital mortality in patients with acute aortic dissection(AAD). Methods We conducted a retrospective analysis of the clinical data of 445 AAD patients who were admitted to the Second Xiangya Hospital of Central South University and the Changsha Central Hospital from January 2014 to December 2017 within a time interval of ≤14 days from the onset of symptoms to hospital admission, including 353 males and 92 females with the age of 45-61 years. LDH levels were measured on admission and the endpoint was the all-cause mortality during hospitalization. Results During hospitalization, 86 patients died and 359 patients survived. Increased level of LDH was found in non-survivors compared with that in the survived [269.50 (220.57, 362.58) U/L vs. 238.00 (191.25, 289.15) U/L, P<0.001]. A nonlinear relationship between LDH levels and in-hospital mortality was observed. Using multivariable logistic analysis, we found that LDH was an independent predictor of in-hospital mortality in the patients with AAD [OR=1.002, 95% CI (1.001 to 1.014), P=0.006]. Furthermore, using receiver operating characteristic (ROC) analysis, we observed that the best threshold of LDH level was 280.70 U/L, and the area under the curve was 0.624 (95% CI 0.556 to 0.689). Conclusion LDH level on admission is an independent predictor of in-hospital mortality in patients with AAD.