This research analyzes the factors influencing bank efficiency. Bank efficiency is measured by BOPO. Predictable variable use risk, which is proxied with non performance loan (NPL), bank size, and CAR. Population in research is in national banking industry which go public in BEI, research period 2009-2016. Sampling technique used purposive sampling, with criterion of bank have go public before year 2008 and bank publish financial report year 2009-2016. The sample of research are 23 banks. The purpose of this study was to analyze the effect of bank risk, bank size and CAR to efficiency either simultaneously or partially. The analytical technique used multiple linear regression. The results showed simultaneously bank risk, bank size and CAR effect on efficiency. Risks, bank size and CAR affect the efficiency with negative direction. Scale of economics does not apply in the industry of national banks. Increasing the CAR as a countercyclical capital buffer (CCB) to control the occurrence of systematic risk can reduce credit growth, can impact the decrease in bank income. Abstraks DOI: 26.82017/JKP.2017.001 Penelitian ini menganalisis faktor yang mempengaruhi efisiensi bank. Efisiensi bank diukur dengan BOPO. Variabel prediktor digunakan risiko, yang diproksikan dengan non performance loans (NPL), ukuran bank, dan CAR. Populasi dalam penelitian adalah pada industri perbankan nasional yang go publik di BEI, periode penelitian 2009-2016. Teknik sampling digunakan purposive sampling, dengan kriteria bank tersebut telah go public sebelum tahun 2008 dan bank tersebut mempublikasikan laporan keuangan tahun 2009-2016. Sampel penelitian sebanyak 23 bank. Tujuan penelitian adalah untuk menganalisis pengaruh risiko bank, ukuran bank dan CAR terhadap efisiensi baik secara simultan maupun parsial. Teknik analisis yang digunakan regresi linear berganda. Hasil penelitian menunjukkan secara simultan risiko bank, ukuran bank dan CAR berpengaruh terhadap efisiensi. Risiko, ukuran bank dan CAR berpengaruh terhadap efisiensi dengan arah negatif. Scale of economics tidak berlaku di industri bank nasional. Peningkatan CAR sebagai countercyclical capital buffer (CCB) untuk mengendalikan terjadinya risiko sistematis dapat menekan pertumbuhan kredit, dapat berdampak penurunan pendapatan bank. ISSN (print) : 2598-7763 ISSN (online): 2598-7771