BACKGROUND: Hurricane Katrina affected a population with significant levels of chronic disease. OBJECTIVE: The extent to which Hurricane Katrina disrupted treatments is not known but would be useful information for future disaster planning. PARTICIPANTS: 1,043 displaced and nondisplaced English-speaking Katrina survivors ages 18 and older who resided in affected areas before the hurricane. DESIGN and SETTING: A geographically representative telephone survey conducted between January 19 and March 31, 2006. MEASUREMENTS and MAIN RESULTS: The proportions of survivors with chronic illnesses in the 12 months before the hurricane and the extent to which those with chronic illnesses cut back or terminated treatments because of the disaster. Correlates and reasons given by survivors for disrupted treatment were identified. Most (73.9%) Katrina survivors had 1 or more chronic conditions in the year before the hurricane; of these, 20.6% cut back or terminated their treatment because of the disaster. Disruptions in treatment were significantly more common among the non-elderly, uninsured, socially isolated, those with housing needs, or for conditions remaining relatively asymptomatic but still dangerous if untreated. Frequent reasons for disrupted care included problems accessing physicians (41.1%), medications (32.5%), insurance/financial means (29.3%), transportation (23.2%), or competing demands on time (10.9%). CONCLUSIONS: Many Katrina survivors burdened by chronic disease had their treatments disrupted by the disaster. Future disaster management plans should anticipate and address such chronic care needs, with timely reestablishment of primary care services, access to medications, and means to address financial and structural barriers to treatment.