Abstract: This study briefly presents MIRBA (Methodology for Investigation of Risk Based Maintenance) for mobile mooring system. MIRBA is developed based on bow tie analysis and AHP. Bow tie analysis consists of FTA (Fault Tree Analysis) on left part and ETA (Event Tree Analysis) on the right part. FTA is useful to determine the potential causes from critical top event until the undesired events are obtained. ETA (Event Tree Analysis) is helpful to define the possible consequence by relating an initiating event to various consequence models. MIRBA consists of risk management through bow tie analysis, risk mitigation by developing the mitigation plan and risk based maintenance using AHP. MIRBA is aimed to provide a guidance on systematic methodology of risk based decision making which is useful to manage and reduce the risk for offshore platforms.