Acute coronary syndromes (ACSs) can be described as ST-segment elevation or non-ST-segment elevation, including unstable angina. Traditionally, ST-segment elevation ACS has been considered to be more serious, but non-ST-segment elevation ACS has higher mortality rates in the longer term. This article discusses diagnosis, including history taking, clinical examination, electrocardiogram and biochemical markers that help to differentiate between types of non-ST-segment elevation ACSs. Risk stratification and treatment strategies are examined, as well as pharmacological treatments. The nurse’s role in assessment, treatment, ongoing management and discharge practice is discussed.