Religious mass gatherings are increasingly common in Iraq and can harbour considerable public health risks. This study was aimed at determining morbidity and mortality patterns in hospitals in Karbala city, Iraq during the mass gathering for Ashura in 2010. We conducted a cross-sectional study on attendees at the 3 public hospitals in the city. The study period was divided into pre-event, event, and post-event phases. Morbidity and mortality data were obtained from hospital registry books and the coroner's office. About 80% of the 18 415 consultations were at emergency rooms. Average daily emergency room attendance was higher during the event compared with pre- and post-event phases, while average daily admissions decreased. Compared with the pre-event phase, a 7-fold increase in febrile disorders and a 2-fold increase in chronic diseases and injuries were noted during the event phase. There was no difference between the 3 phases for average daily death rate, nor for cause of death.