True white horses are born white and are not to be confused with grey horses which have turned white as a result of a greying factor. There are several genetic factors responsible for white horses. True white horses have a pale skin.

• Dominant white (W-Factor): horses are born white, the eyes are generally dark, the homozygous form (two dominant white genes) is thought to be lethal in the embryonic phase as none has ever been identified.
• White born leopards: usually have some colour over bony prominences (limbs, point of hip etc.).
• White frame overos: homozygous foals born white, but die from lethal white factor.
• White sabinos: homozygous sabinos, usually retain a small patch of colour at the poll.

Apart from greys, certain combinations of diluting genes such as a double cream factor (cremellos or perlinos) or a combination of diluting factors (e.g. champagne and cream) can also appear white – however these often have a slightly orange tinge to the hair and pale blue eyes.