This paper summarizes our recent experience in the use of discrete event simulation software to evaluate the performance of a multi-commodity and multi-modal port system located in Valparaiso, Chile. The project objective was to develop an effective tool to evaluate the port system, improve system efficiency, optimize resource utilization, and help decision makers prioritize projects in support of a growing local economy and population. Discrete event simulation models were developed to study port logistics systems and the dynamic interactions of their various components and cargo types as an integrated whole. The existing port system model was calibrated with the observed data, and then extended to study future planned improvements and determine the system capacity. The work demonstrated that a well-developed and calibrated simulation model can be a valuable tool to evaluate and optimize a complex port system and support making critical decisions.