Mobile agent-based technology has attracted considerable interest in both academia and industry in recent years. Fault tolerance is of paramount importance to integrate mobile agent-based technology into today's e-society. In this paper, we propose a mobile agent-based fault-tolerant execution model and analyze the stochastic nature of mobile agents, including the transaction time from node to node, the life expectancy of mobile agents, and the population distribution of mobile agents. Our approach exploits a new way to design fault-tolerant mobile agent-driven system. Our analysis provides useful tools for effectively estimating the performance of agent-driven systems.