Multinutrient block (MNB) is a supplement with a fairly high water content and included Intermediate Moisture. Thus, it needs to be added such preservatives ingredients, among others, green betel leaf. This also has antiprotozoal characters, so this green betel leaf has an impact on the fermentation process in the rumen. The purpose of this study is to examine the biological quality of MNB added green betel leaf in thin-tailed sheep in terms of consumption, feed digestibility, and nitrogen retention. This study used a randomized design group consisting of 3 treatments and 6 replications. The material used was MNB consisting of 50% molasses, 30% fermented rice straw, 6% clam shell flour, 3% salt, 4% urea, and 7% bentonite. This research involved 18 Thin-tailed Sheep with the weight of 11.94 ± 2,14. The addition of green betel leaf on MNB as much as 0% on T0, 3% on T1 and 6% on T2. Feeding process included commercial concentrate 65%, napier grass 25%, and MNB 10%. Each treatment was implemented on the 6 sheep as the test. The results revealed that the addition of green betel leaf juice in MNB had no significant effect (P>0.05) on the consumption of dry matter, consumption of agrie matter feed digestibility and N retention. Moreover, the provision of green betel leaf juice by 6% in MNB did not result in the consumption, digestibility, and the retention of N value in thin-tailed sheep. This research was conducted and obtained permission from the Faculty of Animal and Agriculture, Diponegoro University Semarang.