Islamic banks take advantage of the profits generated by the transactions in which they participate. The aim of this thesis is to study the determinants of the performance of Islamic banks. What can we learn from their experience? What are the elements to ensure their sustainability? This book is based on a qualitative study - case studies - conducted in Bahrain. The results of this work show that the performance of an Islamic bank as an ethical company operating in an intense culture environment is surely affected not only by internal variables of a quantitative nature but also By internal variables of a qualitative nature such as managerial variables. Finally, this research has shown that the governance system of Islamic banks is one of the determining factors in their performance.