After disasters, treatment of chronic hemodialysis (HD) patients is problematic because of logistic and medical reasons. This study analyzes features of HD practice in the regions affected by the Marmara earthquake that struck northwestern Turkey in August 1999. Questionnaires asking about HD infrastructure, medical/social problems of chronic dialysis patients, and the fate of dialysis personnel after the disaster were sent to dialysis units located in the affected region. Data gathered from eight HD centers that responded to questionnaires were then analyzed. The number of HD centers and machines were 12 and 124, respectively, before the earthquake. The number of weekly HD sessions in the analyzed eight centers declined from 1093 before the disaster to 520, 616, and 729 1 wk, I mo, and 3 mo after the earthquake, respectively. In the effective seven centers, the number of HD personnel was 112 before the earthquake, which dropped to 86 and 94 1 and 3 mo after the disaster, respectively. Overall, there were 439 patients in the analyzed eight centers before the disaster, whereas data were provided on 356 (212 were male; mean age, 47.6 +/- 15.1 yr) dialysis patients. Six patients died, and seven were seriously and 28 mildly injured by the direct effects of trauma. The percentage of patients who received once-weekly dialysis increased from 2.3 to 7.2% within the first week, with a return to lower figures (4.1 and 2.8%) 1 and 3 mo afterward. Despite a decrease in the number of HD sessions, interdialytic weight gain decreased I wk after the disaster and BP measurements did not change significantly before and after the earthquake. A total of 301 and 3 1 patients left their dialysis centers, temporarily and permanently. After catastrophic earthquakes, despite a decrease in the number of HD sessions, patients comply with disaster conditions, likely by strictly following dietary and fluid restrictions.