On August 29, 2005, Hurricane Katrina made landfall resulting in catastrophic damage and flooding to New Orleans, LA, and the Gulf Coast, which may have had significant mental health effects on the population. To determine rates and predictors of symptoms consistent with a diagnosis of posttraumatic stress disorder (PTSD) in New Orleans residents following Hurricane Katrina, we conducted a web-based survey 6 months after Hurricane Katrina made landfall. Participants included 1,542 employees from the largest employer in New Orleans. The prevalence of PTSD symptoms was 19.2%. Predictors of PTSD symptoms in a multivariate-adjusted regression model included female sex, non-black race, knowing someone who died in the storm, not having property insurance, having had a longer evacuation, a much longer work commute compared to before Hurricane Katrina, and currently living in a newly purchased or rented house or in a temporary trailer. Despite universal health coverage and the benefits of an employee assistance program for all employees, only 28.5% of those with PTSD symptoms had talked to a health professional about the events of Hurricane Katrina or issues encountered since the storm. A significant burden of PTSD symptoms was present 6 months following Hurricane Katrina among a large group of adults who had returned to work in New Orleans. Given their key role in the economic redevelopment of the region, there is a tremendous need to identify those in the workforce with symptoms consistent with PTSD and to enhance treatment options. The strong relationship between displacement from one's pre-Katrina residence and symptoms of PTSD suggests a need to focus resource utilization and interventions on individuals living in temporary housing.