The objective of this study was to determine the impact of High Rumen Undegraded Protein (HRUP) supplementation to blood urea nitrogen and reproduction performance in early lactation dairy cows. Twelve early lactation Friesian Holstein cows were divided into two groups. Six cows were used as a control group and other 6 cows as HRUP group. Both control and HRUP group obtained basal diet with forage to concentrate ratio 60:40 (DM basis), but different concentrate composition for each groups. Rumen undegraded protein for control group was 27.47% and HRUP group was 32.78%. Feeding twice daily, morning and afternoon. Drink water was given by ad libitum. The observed variable were feed intake, performance reproduction (postpartum mating, service per conception, days open) and Blood Urea Nitrogen (BUN). The results indicated that postpartum mating (91.83±31.16 vs. 81.33±19.83 day), service per conception (1.50±0.55 vs. 1.17±0.41 time) and days open (142.33±66.87 vs. 97.33±41.52 day) between controls and HRUP group were not significant (p>0.05). The average BUN value between controls (15.58±1.99 mg dLG 1) and HRUP group (18.09±1.50 mg dLG) were significant (p<0.05). The conclusion is HRUP supplementation in early lactation dairy cows would be impact on BUN value, but no impact on reproduction performance of dairy cows.