History and Objectives: Considering the high incidence of mumps and its complications and mortality and for determination of the role of environmental factors, this study was carried out on children with complications of mumps in hospitals of Tehran university during the years 1993-1997.

Materials and Methods: This study was performed on existing data of medical records with a diagnosis of mumps. Personal characteristics, time of hospitalization, medical costs, symptoms and clinical manifestations, complications and history of vaccination were evaluated and recorded.

Results: During the study, 305 qualified children were examined. Their average age was 8.4 year and 76% of them were male and 24% were female. Vomiting, headache, neck stiffness and Kerning symptom were recorded in 96%, 92%, 75% and 30% of cases. In CSF, an average of 295 WBC and 80% lymphocyte was obtained. In addition, 91.7% of them had a history of vaccination and they have hospitalized after an average of 4.5 days.

Conclusion: There is a high incidence of complications for mumps and with no vaccination the incidence increases. Performing vaccination for two times at ages 14-18 months and 6th year is strongly recommended.