Background and Objectives: Influenza vaccination is one of the most important ways to prevent influenza acquisition in healthcare staff. This study was conducted to determine the cumulative incidence rate of side effects associated with influenza vaccination among healthcare staff in some of the hospitals in Shiraz.Methods: This descriptive study was conducted on the staff of a number of hospitals in Shiraz who received influenza vaccine in 1392. Instrument in this study was a researcher-developed questionnaire about common side effects that was collected up to 10 days after the vaccination. Incidence of side effects was reported with 95% confidence interval. The data were analyzed by chi-square test, Fisher's exact test, and univariate logistic regression.Results: From the 450 vaccinated staff, 424 (94.23%) completed the questionnaire.53.8% of vaccine recipients were female and 46.2% male. The mean age of the participants was 34.94 years. Up to 10 days after vaccination, cumulative incidence rate of side effects following vaccination was obtained 21.7% for common cold-like symptoms, 71.2% for muscle pain, 16.5% for pain where the shot was given, 15.3% for fever, 14.4% for runny nose, 12.3% for severe headache, 9% for severe coughing, 0.9% for diarrhea, and 1.7% for abdominal pain (1.7%). No severe side effects such as acute allergic reactions and Guillain-Barré syndrome were reported.Conclusion: The reported incidence rate of side effects in this study, high risk of acquiring disease among health care staff, and their role in controlling influenza epidemics represent the necessity of influenza vaccination in this occupational population.