Background The effects of revascularisation extent on the long-term prognosis of patients with stable angina pectoris and three-vessel disease who underwent percutaneous coronary intervention (PCI) were unknown.Methods The revascularisation extent (RE), which was calculated by baseline syntax score minus residue syntax score divided by baseline syntax score, was initially used in our study.Five hundred and fifty-eight patients presenting with stable angina pectoris and three-vessel disease were assigned to and compared among tertiles according to RE and clinical outcomes.The primary endpoint wasthe major adverse cardiovascular event (MACE), a composite of cardiacdeath, nonfatal myocardial infarction (MI), and any repeat revascularisation.Results The median follow-up period was 56.9 months (IQR 52.1 to 63.6).The incidence of MACE increased significantly as RE increased (13.3%, 31.4% and 44.1%, log-rank p<0.001).The same tendency was observed in occurrences of target-vessel failure (TVF: a composite of cardiac death, myocardialinfarction, or target-vessel revascularisation) (8.8%, 20.3% and 28.4%, log-rank p<0.001), repeat revascularisation (11.8%, 26.2% and 35.6%, log-rank p<0.001) and MI (1.1%, 2.9% and 12.6%, log-rank p<0.001).Multivariate analysis confirmed the tendencies mentioned above.Conclusion For patients presenting with stable angina pectoris and three-vessel disease, the increasing extent ofrevascularisation resulted in a less favourable prognosis.