Patients with acute coronary syndrome (ACS) need to be risk stratified to deliver the most appropriate therapy. The GRACE and TIMI risk scores have penetrated contemporary guidelines with the former most commonly used in clinical practice. However, ACS prediction models need to be re-evaluated in contemporary practice with evolving diagnostic and treatment options. Moreover, the increased availability of percutaneous coronary intervention (PCI) as a treatment option for ACS combined with an expanding case mix and emphasis on quality control have triggered the creation of PCI specific prognostic models. These allow clinicians and patients to have an understanding of expected outcomes following PCI by predicting outcomes in-hospital to 5 years following intervention. The aim of this review is to evaluate the most recognized and studied ACS/PCI risk models, focusing on their strengths and limitations, and to assess the need for more robust tools to predict outcomes in a period of constantly advancing technologies and changing patient demographics.