The identification system of horses used in Poland is based on the old classification of coat colours which does not include all colours based on colour inheritance patterns. As a result, some colours are incorrectly described. In order to evaluate the scale of the problem, the accuracy of colour identification was assessed by verifying 5779 pedigrees of horses of three different breeds. The verification was performed based on the colour inheritance patterns using a classification of discrepancies. Such discrepancies were detected in 26 cases and related mainly to diluted colours and black. The problem, however, should not be neglected. The number of incorrectly described horses is probably higher, since not all discrepancies can be detected based only on breeding records. The study demonstrated that some errors could be avoided by updating the classification of coat colours. However, a complete elimination of errors is impossible without genetic testing.