This study was undertaken to estimate genetic parameters for earnings using a total of 9,534 annual earning records from 3,851 horses that had raced from 1990 to 1995. Results obtained were as follows. The annual earnings showed a non-normal distribution, skewing extremely to the right. However, after being standardized by age-birth year groups, the annual earnings appeared to have an almost normal distribution. The unraced ratio per year among 2 year old horsed was highest(44.5%). Consequently, the annual earnings were the lowest compared to other age groups. Heritability and repeatability of the standardized annual earnings were 0.166 and 0.303, respectively. These results suggested that the annual earnings should be standardized by means and standard deviations of age-birth year, groups, considering the phenotypic and genetic correlations between annual earnings and standardized annual earnings were 0.676 and 0.817, respectively.