Penelitian yang dilakukan ini dalam mencari pengaruh tingkat protein dan lisin terhadap efisiensi lisin dan penggunaan protein netto pada ayam kampung yang diperlihara sampai umur 12 minggu. Penelitian yang dilakukan menggunakan 240 ekor ayam kampung (unsex). Model rancangan yang diganakan dalam penelitian ini yaitu Rancangan Acak Lengkap (RAL) faktorial 2 x 3 menggunakan 4 ulangan, sehingga terdapat 24 perlakuan dan setiap perlakuan unit percobaan berisi 10 ekor ayam. Perlakuannya meliputi P1L1 (protein 17% + lisin 0,6% ransum), P1L2 (protein 17% + lisin 0,7% ransum), P1L3 (protein 17% + lisin 0,8% ransum), P2L1 (protein 14% + lisin 0,6% ransum), P2L2 (protein 14% + lisin 0,7% ransum), P2L3 (protein 14% + lisin 0,7% ransum). Pengamatan parameternya meliputi efisiensi lisin dan penggunaan protein netto. Analisa data lanjutan menggunakan analisis uji F untuk mengetahui pengaruh perlakuan, dilanjutkan dengan uji Duncan pada tingkat probabilitas 5% jika ditemukan pengaruh nyata. Hasil penelitian ini menunjukkan bahwa munculnya interaksi protein dan lisin ransum yang nyata (P<0,05) terhadap efisiensi lisin ayam kampung pada umur 12 minggu dengan memberikan hasil yang terbaik pada perlakuan ransum P2L1 (protein 14% dengan lisin 0,6%) dan tidak ada interaksi tingkat protein dan lisin ransum yang nyata (P>0,05) terhadap penggunaan protein netto (PPN) pada ayam kampung umur 12 minggu. Berdasarkan hasil penelitian disimpulkan bahwa efisiensi lisin yang optimal dalam ransum pada Protein 14% dan Lisin 0,6% dan tidak memberikan pengaruh dari parameter penggunaan protein netto. ABSTRACT This study aimed to determine the effect of protein and lysine levels on lysine efficiency and netto protein utilization in native chickens raised up to 12 weeks of age. The research utilized 240 unsexed native chickens. A completely randomized design (CRD) with 2 × 3 factorial consisting of 4 replications and 24 experimental units, with each unit containing 10 chickens. The treatments included P1L1 (17% protein + 0.6% lysine in the diet), P1L2 (17% protein + 0.7% lysine in the diet), P1L3 (17% protein + 0.8% lysine in the diet), P2L1 (14% protein + 0.6% lysine in the diet), P2L2 (14% protein + 0.7% lysine in the diet), and P2L3 (14% protein + 0.8% lysine in the diet). Observed parameters included lysine efficiency and net protein utilization. Data analysis involved an F-test to identify treatment effects, with followed by Duncan's multiple range test at a 5% significance level for significant results. The results revealed a significant interaction (P<0,05) between protein and lysine in the diet on lysine efficiency in 12-week-old native chickens, with the best result observed in the P2L1 treatment (Protein 14% and lysine 0.6% in the diet). However, there was no significant interaction (P>0.05) between protein and lysine levels on net protein utilization at 12 weeeks of age. Based on the findings, it can be concluded that optimal lysine efficiency in the diet is achieved with 14% protein and 0.6% lysine, while netto protein utilization is not significantly affected by the treatments.