Background Since permanent polymer is implicated in adverse events associated with delayed vessel healing after drug eluting stents (DES) implantation,great efforts have been made to develop more biocompatible DES with biodegradable polymer or without polymer.The present study aimed to evaluate the safety and efficacy of polymer free paclitaxel-eluting stents (PF-PES) in comparison with permanent polymer sirolimus-eluting stents (PP-SES) in patients with acute ST-segment elevation myocardial infarction (STEMI).Methods Patients with STEMI were randomly assigned to receive PP-SES (n=55),and PF-PES (n=50).The 6-month angiographic and 1-year clinical outcomes were compared between the two groups.Target lesion failure (TLF) was defined as the composite of cardiac death,recurrent nonfatal myocardial infarction (Re-MI),or target lesion revascularization (TLR).Results Follow-up angiography at six months was performed in 72.7％ of the PP-SES group and 70.0％ of the PF-PES group (P=0.757).The two groups had comparable angiographic outcomes including minimal luminal diameter,diameter stenosis,late loss and binary restenosis.All patients were clinically followed up to one year.The two groups had similar clinical outcomes with relatively low rates of target lesion failure (10.9％ PP-SES vs.12.0％ PF-PES,P=0.861) and definite or probable stent thrombosis (1.8％ PP-SES vs.2.0％ PF-PES,P=1.000) at one year.Conclusions The present study suggests that the safety and efficacy of PF-PES in the setting of STEMI are comparable to PP-SES.Further randomized trials with larger study populations are needed to get definite conclusions.