Horses are measured using a unit of measure called a "hand". A hand equals about four inches.

When the British discovered polo in Persia, the average polo pony was about twelve hands high. The first height limit for polo ponies was set in 1976 at fourteen hands. In 1986 the limit was raised to fourteen hands two inches. In 1919 limits were abolished.

Today most polo ponies are of normal height, averaging fifteen hands one inch. However, it is not unusual for a pony to be over sixteen hands.

Although they are not recognized as a distinct breed, Polo ponies are truly unique horses that combine the traits of a number of breeds. Next to a player's skills, the polo pony is the most important factor in polo. And, many times, the pony is the single greatest determinant of the outcome of a match.

Polo demands the quick burst of speed seen in Thoroughbreds. The complexity and strategy of a polo match requires the intelligence of Arabians. And the rapid turn of play in pursuit of the ball necessitates the agility of Quarter Horses.

The English have documented the breeding of polo ponies since 1893. A small thoroughbred stallion named Rosewater holds the title of "foundation sire" for most English ponies.

In the United States, Thoroughbreds are usually bred with Quarter Horses to produce polo ponies.

Since 1930 most of the best polo ponies have been produced in Argentina. The Argentines cross Thoroughbreds with their local Criollo horses.

A renewed interest in polo has created a larger market for the Argentines, who take time to produce "a made pony" that loves to play the game.