Mobile agent technology becomes one of the dominant technologies in the information systems and network applications nowadays. For this reason, reliability mechanisms for mobile agents have to be established. In the context of mobile agents, fault-tolerance prevents a partial or complete loss of the agent. Several approaches are designed and developed for fault tolerant mobile agent execution. They have different strengths and weaknesses, have different constraints and assumptions and address different environments. Because of this variety, it is often difficult to choose the approach that best suited to our application. The research proposes three main approaches to handle the fault tolerant of the mobile agent execution. The model is named as: Fault Tolerant Mobile Agent execution System “FTMAS”. The proposed approaches are: the Centralized approach, the Windowing approach and the Centralized Windowing approach. A classification of the various failure variations that agent may suffer from during and after its execution is suggested in the research too.