Abstract Background It is well known that there are major differences between the Japanese and Western population regarding the incidence of ischemic heart disease and stroke. The purpose of this study was to evaluate differences of patients’ characteristics between Belgian and Japanese cohort with acute type A aortic dissection. Methods In 487 patients (297 male patients, mean age 61.9 ± 12.2 yrs) who underwent surgery for acute type A aortic dissection, baseline preoperative and intraoperative data were collected. Belgian patients (n = 237) were compared to Japanese patients (n = 250). Clinical data included patient demographics, history, status at presentation, imaging study results and intraoperative findings. Results The Japanese cohort had significantly more women (48.8% vs. 28.7%, p < 0.0001), lower BMI (24.2 vs. 26.4, p < 0.0001) and lower prevalence of hypertension (49.2% vs. 65.8%, p = 0.0002). More DeBakey type I dissections and less type III dissections with retrograde extension were reported in Belgium than in Japan (77.2% vs. 48.4%, p < 0.0001, 3.4% vs. 38.7%, p < 0.0001, respectively). More entries were found in the ascending aorta (78.5% vs. 58.5%, p < 0.0001) and aortic arch (24.9% vs. 13.7%, p = 0.0018) in Belgian patients than in Japanese patients, who had more entries in the descending aorta or undetected entries. Conclusions In acute type A aortic dissection, Belgian patients reveal striking differences from Japanese patients regarding gender distribution, entry tear location and type of dissection. Japanese women are more likely to develop acute type A aortic dissection than Belgian women. (234 words).