The objective of this study was to develop adjustment factors for racing distances, using a total of 53,097 racing records from 2,928 horses that had raced from January, 1990 to December, 1993. Results obtained were as follows. 1. Skewedness for racing time by each distance was near zero, and the data skewed a little to the right. 1Me entire data, however, was almost normally distributed. 2. Racing frequencies for progeny per sire decreased with increasing racing distance. In the case of the 2,200m race in which the largest number of exellent horses took part in competition, one record per sire was most widely distributed and the proportion was about 88% of all data Considering the unique distribution of Korean racing data, it was suggested that the entire data for various distances should be used for the genetic evaluation of racing horses. 3. Contemporary group effect for racing time made up about 40% of total variation, and this implied that contemporary effect was one of the important environmental factors for the genetic evaluation of racing horses. 4. Variances adjusted by additive factors showed homogeneous values for various distances, while those adjusted by multiplicative factors deviated greatly from unadjusted data, with increasing racing distances. 5. Correlations between PTA`s for additive adjusted and unadjusted records were shown to be about 0.99. This fact led to the suggestion that the additive adjustment factors would be more practical and reasonable for adjustments of racing distances.