This study explains the evaluation of Internal Control System to support the effectiveness of credit lending to small and medium-sized enterprises in PT Bank Rakyat Indonesia Mlati branch office. This study aims to evaluate the Internal Control System applied in lending credit to small and medium-sized enterprises in PTBank Rakyat Indonesia Mlati branch office has been done by a proper procedure or not. Based on the results of the research that has been done, the procedures of credit lending are in accordance with the terms and conditions set by the bank. The Internal Control System that has been implemented has been effective, efficient and adequate in accordance with the elements of Internal Control. It can be seen from the elements of Internal Control contained in the theories book and theories obtained during lectures.