Aims Eisenmenger syndrome (ES) is associated with considerable morbidity and mortality. Therapeutic strategies have changed during the 2000s in conjunction with an emphasis on specialist follow-up. The aim of this study was to determine the cause-specific mortality in ES and evaluate any relevant changes between 1977 and 2015. Methods and results This is a retrospective, descriptive multicentre study. A total of 1546 patients (mean age 38.7 +/- 15.4 years; 36% male) from 13 countries were included. Cause-specific mortality was examined before and after July 2006, 'early' and 'late', respectively. Over a median follow-up of 6.1 years (interquartile range 2.1-21.5 years) 558 deaths were recorded; cause-specific mortality was identified in 411 (74%) cases. Leading causes of death were heart failure (34%), infection (26%), sudden cardiac death (10%), thromboembolism (8%), haemorrhage (7%), and peri-procedural (7%). Heart failure deaths increased in the 'late' relative to the 'early' era (P = 0.032), whereas death from thromboembolic events and death in relation to cardiac and non-cardiac procedures decreased (P = 0.014, P = 0.014, P = 0.004, respectively). There was an increase in longevity in the 'late' vs. 'early' era (median survival 52.3 vs. 35.2 years, P < 0.001). Conclusion The study shows that despite changes in therapy, care, and follow-up of ES in tertiary care centres, all-cause mortality including cardiac remains high. Patients from the 'late' era, however, die later and from chronic rather than acute cardiac causes, primarily heart failure, whereas peri-procedural and deaths due to haemoptysis have become less common. Lifelong vigilance in tertiary centres and further research for ES are clearly needed.