Selection for milk production over the years has caused many problems, including the reproduction disorders. The purpose of this study was to estimate the parameters of body condition score with random regression test day records and the correlation of these traits with reproductive traits to improve reproductive performance. Based on 42,040 data from 6978 first lactation animals in the years 2005 to 2013 were collected in a cooperative Vahdat in Esfehan, were used. Pedigree information was included 88,448 animals born between the years 1993 to 2012. Fertility traits included open days, non-return rate in 56 day and number of services per conception in second pregnancy. Estimates of genetic and environmental variance-covariance with random regression animal model using the DMU software in AIREML method. Heritability of body condition score at different days was in the range of 0.09 to 0.26 with average 0.13. Heritability of open days, non-return rate in 56 day and number of services per conception in second pregnancy with 2-trait was 0.03, 0.05 and 0.02 respectively. Cows breeding values calculated at 305 days and was low for many cows. The high correlation between the different days of lactation test day records showed that same genes affecting body condition score. The correlation between body condition score and fertility traits was calculated from covariance random regression coefficient in 2-traits model. Weak and negative correlation between body condition score and open days were obtained (-0.10 to -0.16) which was the highest in early lactation. Also, between body condition score with non-return rate in 56 day and number of services per conception in second pregnancy was, respectively, the positive genetic correlation (0.11 to 0.26) and negative (-0.06 to -0.30). This relationships showed these 2-traits changed together. In other word, the cows with more reduce in condition score (1 ) has more number of service per conception and reduce pregnancy in first lactation. The results of this study suggested that the relationships between body condition score and reproduction traits, cows body condition score with high genetic control has improved reproduction. Keywords : Body Condition Score, Genetic Relationship, Reproduction traits, Random Regression, Holstein