Aspirin is a foundation drug of the pharmaceutical industry originally derived as an analgesic/anti-inflammatory agent but serendipitously discovered to have use as a prophylactic drug for major adverse cardiovascular events (MACE). Its modern-day utility in this latter role relies on its efficacy/safety balance in a contemporary population where, at least in high-income countries, age-standardised incident rates for MACE are falling, and where there are now competing therapeutic agents. Its future may be determined by its potential role as a chemoprophylactic or adjunct agent for cancer or other disease states. It therefore will continue to be the subject of further clinical research.