This article lists the tributaries of the River Thames from the sea to the source, in England. It includes significant backwaters and waterways that have confluences with the main stream of the River Thames. Most of the tributaries are natural, but a few were man-made.
In addition to those listed, the River Medway shares the Thames Estuary, and near Oxford the River Thames is also named The Isis.
The average discharge is taken from the lowest point at which measurements are taken, which may be upstream of the confluence.