The River of Bain is located in Lincolnshire, in England. It is said to be the tributary of the River of Witham. The River Bain rises at the Lincolnshire Wolds at Ludford; it is a village that is located on the Viking Way Long Distance footpath.

The river flows through the village of Burgh on Bain. It also passes through. Biscathorpe, Donington on Bain, Hemingby and Goulceby with Asterby, by the time the river reaches Horncastle and is joined by the River Waring.

The River of Bain contains very significant populations of Bream, Rudd, Roach and Chub. The river also contains smaller pieces such as the Millers Thumb.