Abstract Background Several studies have found a so-called weekend effect that patients admitted at the weekends had worse clinical outcomes than patients admitted at the weekdays. We performed this retrospective cohort study to explore the weekend effect in four major cardiovascular emergencies in Taiwan. Methods The Taiwan National Health Insurance (NHI) claims database between 2005 and 2015 was used. We extracted 3811 incident cases of ruptured aortic aneurysm, 184,769 incident cases of acute myocardial infarction, 492,127 incident cases of ischemic stroke, and 15,033 incident cases of pulmonary embolism from 9,529,049 patients having at least one record of hospitalization in the NHI claims database within 2006 ~ 2014. Patients were classified as weekends or weekdays admission groups. Dates of in-hospital mortality and one-year mortality were obtained from the Taiwan National Death Registry. Results We found no difference in in-hospital mortality between weekend group and weekday group in patients with ruptured aortic aneurysm (45.4% vs 45.3%, adjusted odds ratio [OR] 1.01, 95% confidence interval [CI] 0.87–1.17, p = 0.93), patients with acute myocardial infarction (15.8% vs 16.2%, adjusted OR 0.98, 95% CI 0.95–1.00, p = 0.10), patients with ischemic stroke (4.1% vs 4.2%, adjusted OR 0.99, 95% CI 0.96–1.03, p = 0.71), and patients with pulmonary embolism (14.6% vs 14.6%, adjusted OR 1.02, 95% CI 0.92–1.15, p = 0.66). The results remained for 1 year in all the four major cardiovascular emergencies. Conclusions We found no difference in either short-term or long-term mortality between patients admitted on weekends and patients admitted on weekdays in four major cardiovascular emergencies in Taiwan.