OBJECTIVES: Naturally occurring catastrophic events not only disrupt economic activity but also impact access to essential health services. The purpose of this study is to quantify the long-term impact of Hurricane Katrina on continuously-eligible epilepsy patients’ healthcare utilization pre-and post-Hurricane Katrina (August 29, 2004-August 28, 2007). METHODS: This study was a population-based retrospective analysis of the Louisiana Medicaid database.  Frequency counts of demographic variables age, gender, race and region were computed.  Segmented regression analysis was applied to the longitudinal data to analyze changes in emergency room (ER) utilization, the number of patients receiving anti-epileptic medication, the total number of prescriptions utilized and the average cost of pharmacy claims.  In effect, the dependent variables were regressed against 1) total time (months); 2) Katrina as a discrete event; and 3) time post-Katrina (months). RESULTS: A total of 1371 epileptic patients in the Louisiana Medicaid population was found of which 2/3rds were 18-64 years of age, 49% African-American and 53.1% were males.  Patients were primarily from Baton Rouge (44%), New Orleans (36%) and Acadiana (21%).  Results of segmented regression analysis revealed that ER utilization was significantly related to all three time variables. Katrina as a discrete event was statistically significant in relation to the number of epileptic patients receiving prescriptions and the number of prescriptions utilized, whereas the average cost per prescription claim was related to both total time and time after Katrina. CONCLUSIONS: Hurricane Katrina was found to be a key factor in the significant decrease in the number of patients that received anti-epileptic medications post-Hurricane Katrina.  This may also explain why there were significant decreases in the numbers of ER visits, anti-epileptic medications obtained and the average cost of paid claims for anti-epileptic drugs. In effect, Katrina had both short- and long-term negative effects on epileptic patients’ access to care.