he concept of mudharabah in sharia financial institutions is not fully in accordance with the concepts in classical fiqh. such as Sharia Financial Institutions (LKS) applying the concept of mudharabah in financing, the bank acting as shahibul maal ask for a guarantee or collateral to mudharib, whereas according to some Imam Madzhab forbade it. The National Sharia Council (DSN) is an institution in which it consists of scholars, practitioners and experts in its field, who are given the task of instilling Syar'i values in products run by LKS and monitoring all transactions applied in LKS. Implementation of guarantee on mudharabah financing based on DSN fatwa no. 0 7 DSN-MUI / IV / 2000. The existence of Collateral is basically not an obligation, in the process it becomes a must when customers want to get financing. This is what underlies the author to see the existence of collateral in mudharabah financing in LKS. This research is a descriptive analytic research using data about mudharabah financing contract implementation, books, documents, works, or writings relevant to this study then analyze it from the perspective of Islamic law