Predicting patient enrolment in clinical trials is challenging. While early enrolment forecasts are often evolving, they are required by clinical supply groups to establish drug demand. The link between enrolment forecast and drug waste can be a source of frustration between clinical operations and clinical supply groups. How can supply planners create accurate drug forecasts from uncertain enrolment forecasts? In this article, Louise Oliver and Luke Moyer from the Almac Group contend that synergy is the key to optimising supply and maximising patient benefits.