Several large trials have shown that the risk of stroke in patients wi
th non-valvar atrial fibrillation is reduced by treatment with warfari
n. Implementing this research evidence requires not only an understand
ing of the trials' results and of the changes that they imply for clin
icians' treatment decisions but also an appreciation of the organisati
on, quantity, and quality of services required to support these change
s. Understanding of these implications is crucial for developing servi
ces that allow changes in practice to produce reductions in stroke inc
idence while minimising the risks of treatment. This article considers
the developments in service provision that will probably be required
to support the changes in clinical practice suggested by the trials' r
esults. These services will be provided largely by doctors, and their
development has implications for doctors in both primary and secondary
care.