Sorrel is one of the most common coat colors in horses, ranging from reddish-gold to deep burgundy. The term probably comes from the color of the flower spike of the sorrel herb.

Sorrel coloration can be distinguished from dun by the fact that a dun horse has a darker mane and tail than the rest of its coat, may have bars of darker color on the shoulder and forelegs, and also possesses a narrow, dark line down the middle of the back. A very dark sorrel and a very bright blood bay may look similar except for the black mane, tail and lower legs on the bay. Light-colored sorrels - sometimes called "blond sorrels," especially if they have flaxen manes and tails - can also look similar to dark palominos; however, true palomino coloration is the result of a horse's being heterozygous for the creme gene. They can be distinguished by the fact that sorrel coloration breeds true, while genuine palomino coloration does not.

The term "chestnut" is also often used to describe horses of a reddish-brown color. Chestnut was the word originally used in England, while the term "sorrel" originated in the United States. Both terms are now common in both countries. Some horse enthusiasts insist that chestnut and sorrel are two distinct colorations, but there is no clear consensus on what the distinction is. Some argue that "sorrel" should only be used to describe lighter shades, or shades with a very clear reddish tint, while "chestnut" denotes darker shades or shades with more brown in them. Others define the two terms in precisely the opposite way. Some say that sorrel is a self color, and should only be used to describe horses whose mane, tail and legs are the same color as the rest of the coat, with the exception of possible white markings below the knee or hock; others use "sorrel" only for reddish-brown horses with flaxen manes and tails, and use "chestnut" when reddish-brown coloration appears as a self color. Some suggest that the difference is not in color but of usage: horses ridden with Western reins are sorrel and horses ridden with English reins are chestnut. Many organizations simply avoid the whole fuss and choose one of the two terms to denote all reddish or brown colorations.

Horse coat colors