Background Ischemia and malperfusion are strong predictors of poor postoperative outcomes in type A acute aortic dissection (TAAAD). Serum lactate is an accurate surrogate point‐of‐care marker of malperfusion. The aim of this study is to investigate the correlation between lactate, in‐hospital outcomes, and 1‐year survival following TAAAD repair. Methods One hundred and thirty‐two patients underwent operative repair of TAAAD over a 4‐year period at our institution 128 patients had serum lactate measurements at three stages peri‐operatively‐preoperatively, at the end of cardiopulmonary bypass (post‐CPB) and 6 h postintensive care unit (ICU) admission. The primary outcomes were in‐hospital mortality and 1‐year survival. The secondary outcomes were the incidences of in‐hospital morbidities. Results Patients were divided into two groups: 88 (68.8%) with normal lactate and 40 (31.2%) with elevated lactate (>2.2 mmol/L). Lactate measured preoperatively (odds ratio 1.52, 95% confidence interval 1.17–2.07, p < .01), post‐CPB (1.34, 1.14–1.64, p < .01) and 6 h post‐ICU admission (1.29, 1.08–1.55, p < .01) was an independent predictor of in‐hospital mortality. Following adjustment for the Penn Classification, lactate continued to have a significant correlation with in‐hospital mortality at all three timepoints. There was a higher incidence of complications in the elevated lactate group and especially hemofiltration (20% vs. 9.1%, p = .08). 1‐year survival was similar in both groups (p = .23). Conclusions There is a direct correlation between elevated serum lactate and postoperative mortality after TAAAD repair, which is independent of the Penn Classification status on admission.