While offering many practical benefits for distributed applications, mobile agent systems pose some fundamental security challenges. In this paper, we present a new approach to mobile agent security which helps to address some of these challenges. We present a new technique, which we refer to as trust enhanced security, and apply it to mobile agent-based systems; this new technique advocates a shift in security solutions from security-centric to trust-centric. This extends the traditional security mechanisms by enabling trust decisions through explicit specification and management of security-related trust relationships. The integration of the trust decisions into security decision-making process leads to our trust enhanced security performance. A formal trust model is proposed and is incorporated into the development of a novel trust management architecture-MobileTrust for mobile agent-based applications. We have conducted detailed practical investigations to evaluate and validate the emergent properties of the trust enhanced security technique. We present and discuss the key results in this paper.