viii ABSTRACT This research that aims to find out how the influence of the implementation of Good Corporate Governance on sharia bank performance and also to reveal whether there is an difference on sharia bank performance before and after the implementation of Good Corporate Governance. The object of this research is Bank Syariah Mandiri which was selected using a non-probability sampling technique. The type of this research is comparative research and associative research. Data collection was obtained by the documentation method, documentation on this research was conducted from secondary data in the form of financial statements Bank Syariah Mandiri. The dependent variable used is Return on Assets (ROA) accompanied by an independent variable consisting of a board of commissioners, board of directors, audit committee and sharia supervisory board. Based on the results of tests conducted showed that the variables of the board of commissioners, board of directors, audit committee and sharia supervisory board (DPS) significantly influence the performance of Bank Syariah Mandiri simultaneously by 86%. On a different test, the test results show that there are significant differences between the performance of Bank Syariah Mandiri before and after the implementation of Good Corporate Governance seen from the Asset and Management ratio. Whereas in the Capital, Earning and Liquidity ratios there were no significant differences between the performance of Bank Syariah Mandiri before and after the implementation of Good Corporate Governance. Keywords: Good Corporate Governance (GCG), Sharia Banking, Board of Commissioners, Board of Directors, Audit Committee, Sharia Supervisory Board, Return on Asset (ROA). ix ABSTRAK Penelitian ini bertujuan untuk mengetahui bagaimana pengaruh dari implementasi kebijakan Good Coprorate Governance (GCG) terhadap kinerja perbankan syariah dan juga mengungkapkan apakah terdapat perbedaan kinerja bank syariah sebelum dan sesudah implementasi kebijakan Good Corporate Governance (GCG). Objek dari penelitian ini adalah Bank Syariah Mandiri (BSM) yang dipilih dengan menggunakan teknik non-probability sampling. Jenis penelitian yang digunakan adalah penelitian komparatif dan penelitian asosiatif. Pengumpulan data diperoleh dengan metode dokumentasi, dokumentasi pada penelitian ini dilakukan dengan mengumpulkan data sekunder berupa laporan keuangan dari Bank Syariah Mandiri (BSM). Variabel dependen yang digunakan ialah Return on Asset (ROA) disertai variabel independen yang terdiri dari dewan komisaris, dewan direksi, komite audit dan dewan pengawas syariah (DPS). Berdasarkan hasil pengujian yang dilakukan menunjukkan bahwa variabel dewan komisaris, dewan direksi, komite audit dan dewan pengawas syariah (DPS) berpengaruh signifikan terhadap kinerja Bank Syariah Mandiri (BSM) secara bersama-sama (simultan) sebesar 86%. Pada uji beda, hasil pengujian menunjukkan bahwa terdapat perbedaan yang signifikan antara kinerja Bank Syariah Mandiri (BSM) sebelum dan sesudah penerapan Good Corporate Governance (GCG) dilihat dari rasio Asset dan Management. Sedangkan pada rasio Capital, Earning dan Liquidity tidak ditemukan adanya perbedaan yang signifikan antara kinerja Bank Syariah Mandiri (BSM) sebelum dan sesudah penerapan Good Corporate Governance (GCG). Kata Kunci: Good Corporate Governance (GCG), Perbankan Syariah, Dewan Komisaris, Dewan Direksi, Komite Audit, Dewan Pengawas Syariah (DPS), Return on Asset (ROA).