A computational grid is a wide-area computing environment for cross-domain resource sharing and service integration. Resource management and load balancing are key concerns when implementing grid middleware and improving resource utilization. Grid resource management can be implemented as a multiagent system with resource advertisement and discovery capabilities if job requests from users are associated with explicit QoS requirements. In this work agent-based self-organization is proposed to perform complementary load balancing for batch jobs with no explicit execution deadlines. In particular, an ant-like self-organizing mechanism is introduced and proved to be powerful to achieve overall grid load balancing through a collection of very simple local interactions. A modeling and simulation environment is developed to enable performance of the ant algorithm to be investigated quantitatively. Simulation results included in this work illustrate the impact of different performance optimiz...