OBJECTIVE: The authors examined the disruption of ongoing treatments among individuals with preexisting mental disorders and the failure to initiate treatment among individuals with new-onset mental disorders in the aftermath of Hurricane Katrina. METHODS: English-speaking adult Katrina survivors (NEuro Surveillance (Bulletin Europeen Sur Les Maladies Transmissibles; European Communicable Disease Bulletin)1,043) responded to a telephone survey administered between January and March of 2006. The survey assessed posthurricane treatment of emotional problems and barriers to treatment among respondents with preexisting mental disorders as well as those with new-onset disorders posthurricane. RESULTS: Among respondents with preexisting mental disorders who reported using mental health services in the year before the hurricane, 22.9% experienced reduction in or termination of treatment after Katrina. Among those respondents without preexisting mental disorders who developed new-onset disorders after the hurricane, 18.5% received some form of treatment for emotional problems. Reasons for failing to continue treatment among preexisting cases primarily involved structural barriers to treatment, while reasons for failing to seek treatment among new-onset cases primarily involved low perceived need for treatment. The majority (64.5%) of respondents receiving treatment post-Katrina were treated by general medical providers and received medication but no psychotherapy. Treatment of new-onset cases was positively related to age and income, while continued treatment of preexisting cases was positively related to race/ethnicity (non-Hispanic whites) and having health insurance. CONCLUSIONS: Many Hurricane Katrina survivors with mental disorders experienced unmet treatment needs, including frequent disruptions of existing care and widespread failure to initiate treatment for new-onset disorders. Future disaster management plans should anticipate both types of treatment needs.