In recent months, the term ‘estimand’ has started to appear in clinical trial protocols and reports. The term itself is simple enough, meaning ‘that which is to be estimated’, but its presence acknowledges new thinking about the ways in which the therapeutic success of an intervention should be measured. Murray Edmunds and Adam Dagnall of Watermeadow Medical, Ashfield, summarises some of the key issues and consider ways in which the emergence of estimands could affect day-to-day life in the field of medical communications.