OBJECTIVES: This study aimed to investigate the relationship between post-PCI guideline adherence and 5- year clinical outcomes of post-PCI patients in Hong Kong.  METHODS: Retrospective data and information was retrieved from the PCI registry and electronic patient record system in Prince of Wales Hospital, Hospital Authority. 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention was chosen as reference for post-PCI recommended therapies. Total five post-PCI guideline-recommended therapies were included in analysis for the relationship with 5-year clinical outcomes, the major adverse cardiac events (MACE).  RESULTS: Total 276 (68.3%) PCI patients completed 5-year follow-up. Forty-four (15.9%) patients experienced MACE in the 5-year period with 23 (52.3%) as cardiac death, 11 (25%) as non-fatal myocardial infraction, and 10 (22.7%) as target vascular revascularization. Only 40 (14.5%) patients fully adhered to all five guideline-recommended therapies with a mean total percentage adherence of 77.8%. Diabetes management (95.2%) was the most adherent therapy and lipid management was the least adherent therapy (40.7%). Only 64.73% of patients adhered to dual antiplatelet therapy with 89.9% and 71.0% of patients adhered to aspirin and clopidogrel respectively.  Five-year total percentage adherence and dual antiplatelet therapy adherence did not significantly correlate with the 5-year clinical outcomes in post-PCI patients. However, one of the guideline-recommended therapies, the adherence to aspirin was significantly associated with reduced 5-year rates of MACE (adjusted OR 0.071, 95% CI 0.005-0.981, p =0.048) and cardiac deaths (adjusted OR 0.036, 95% CI 0.002-0.742, p =0.031).  The adherence of dual antiplatelet therapy and lipid management were significant associated with reduced non-cardiac deaths (adjusted OR 0.224, 95% CI 0.072-0.700, p =0.031) and numbers of hospital admissions (adjusted beta -0.135, 95% CI -1.126 to -0.035, p =0.037) respectively.  CONCLUSIONS: Adherence to aspirin, dual antiplatelet therapy, and lipid management were associated with better 5-year clinical outcomes in post-PCI patients.