This research was carried out to study of productive and reproductive traits (milk (Milk), fat yield and percentage (Fat and FatP), protein yield and percentage (Pro and ProP), lactation length (LL), dry period (DP), age at first calving (AFC) and calving interval (CI)) of Holstein dairy cows in arid and semi aridclimate of Iran. Data were collected of 4805 and 58781 first lactation Iranian Holstein dairy cows in arid and semi-arid climate, respectively during 1996 to 2009 by the Animal Breeding Center of Iran. Variance components were estimated by restricted maximum likelihood method using DMU package. The estimated heritabilities in arid and semi-arid climate were 0.23, 0.27, 0.39, 0.28, 0.41, 0.04, 0.006, 0.23 and 0.04 of production and reproductive traits (Milk, Fat and FatP, Pro and ProP, LL, DP, AFC and CI), respectively and 0.21, 0.18, 0.08, 0.11, 0.34, 0.03, 0.02, 0.10 and 0.05, respectively. The current result showed least square mean of traits in semi-arid climate was higher than arid climate for all traits and it can be due to better management practices however for CI trait should be less(P<0.05).

Keywords