In February 1999, the Maryland Department of Health and Mental Hygiene initiated pandemic influenza planning for the state of Maryland. This process involved several major steps, including the development of the Maryland Pandemic Influenza Preparedness Plan, and culminated in a high-level tabletop exercise to test the plan in April 2004. During the tabletop exercise, participants were presented with nine different fictitious scripts encompassing a single scenario. They were asked to respond to the information presented in each script, discuss organization-specific questions posed by the exercise facilitator, and make decisions regarding action steps that their organization would take in response to the various issues raised. The exercise identified a number of important gaps that need to be addressed, including (1) additional surge capacity specific to a pandemic, (2) greater understanding of the realities and implications of pandemic influenza among elected officials and decision-makers, (3) coordination of pandemic influenza planning with the existing emergency response infrastructure coupled with additional training in incident command, (4) further steps to operationalize several aspects of the Maryland Pandemic Influenza Preparedness Plan, and (5) additional federal guidance.