Long-term clinical outcomes of new-generation drug-eluting stents in complex anatomic and clinical settings are not well defined. This study assessed the impact of patient and lesion complexity on 2-year outcomes after coronary revascularization with ultrathin strut biodegradable-polymer (BP) sirolimus-eluting stents (SES) versus durable-polymer (DP) everolimus-eluting stents (EES). In a prespecified analysis of the BIOSCIENCE randomized trial (NCT01443104), complex patients (911 of 2,119; 43%) were defined by the presence of acute ST-elevation myocardial infarction (MI); left ventricular ejection fraction ≤30%; renal dysfunction; insulin-treated diabetes; treatment of ostial lesion, bypass graft, unprotected left main lesion; or 3-vessel intervention. The primary end point was target lesion failure (TLF), a composite of cardiac death, target vessel MI, and clinically indicated target lesion revascularization. At 2 years, complex compared with simple patients had a greater risk of TLF (14.5% vs 7.4%, risk ratio 2.05, 95% confidence interval 1.56 to 2.69; p <0.001). The difference was sustained beyond 1 year on landmark analysis. Complex patients had higher rates of the patient-oriented composite end point of death, any MI, or any revascularization (23% vs 14.4%; p <0.001) as well as definite stent thrombosis (1.6% vs 0.4%, p = 0.006). There were no differences in TLF and patient-oriented composite end point between the BP-SES versus DP-EES, consistently among simple and complex patients. In conclusion, patient and lesion complexity had a durable adverse impact on clinical outcomes throughout 2 years of follow-up in this all-comers randomized trial. Safety and efficacy of new-generation BP-SES and DP-EES were comparable, irrespective of complexity status.