Aims: The aim of APPOSITION III was to evaluate the feasibility and performance of the STENTYS Self-Apposing (R) stent (STENTYS S.A., Paris, France) in the setting of primary percutaneous coronary intervention (PCI). Methods and results: APPOSITION III was an international, prospective, multicentre registry. The study population consisted of 965 patients. The rate of the primary endpoint major adverse cardiac events (MACE), defined as the composite of cardiac death, recurrent target vessel myocardial infarction (TV-M[), and clinically driven target lesion revascularisation (CD-TLR), at one year was 9.3%. One-year cardiac death rate was 2.0%, TV-MI rate was 1.3%, CD-TLR rate was 7.4% and definite/probable stent thrombosis (ST) rate was 3.5% (definite ST 2.8%). An interim safety analysis of in-hospital outcomes in the first 400 patients showed higher event rates if post-dilation was not performed, and post-dilations became highly recommended in the remaining cohort. Patients undergoing post-dilation eventually showed a numerically lower one-year MACE rate (8.4% vs. 11.3%, p=0.137). One-year TV-MI (0.8% vs. 2.5%, p=0.027) and definite ST (1.9% vs. 5.0%, p=0.010) rates were significantly lower if post-dilation was performed, with the divergence occurring at <30 days. Conclusions: The use of the STENTYS Self-Apposing (R) stent in the setting of primary PCI was feasible and associated with acceptable cardiovascular event rates which improved when post-dilation was performed.