Background: Infectious diseases are important causes of mortality and morbidity in children and have been a particular concern in pediatrics’ wards. Although, infectious disease are important components of population health in high-income nations, but are often overlooked. The recognition of the factors and infectious agent subtypes could help to prevent further interventions. Up to now, there are limited investigations regarding this important issue.Objectives: We aimed to investigate the pattern of infection in patients admitted to 17th Shahrivar Children's Hospital.Patients and Methods: This is a descriptive cross-sectional study which was conducted in 17th Shahrivar Children's Hospital during August 2008-August 2009. Participants comprised of children aged 1 month to 14 years, who admitted to the hospital. Samples were collected by simple sampling and data were collected by a form including the age, gender, place of inhabitants, season of admission, duration of hospitalization and final diagnosis. Descriptive statistics such as mean, standard deviation, frequency, the maximum and minimum of data were used to analyze the results using SPSS version 16 software.Results: During the study, 4676 children, aged 1 month to 14 years were admitted and 29% (1357) of them were diagnosed with infectious disorders, 1127 infected patients (83.2%) were younger than 5 years. Results demonstrated that the infectious diseases were more frequent in male, winter and residents from urban area. Also, Respiratory tract and gastrointestinal infections had been diagnosed in 40.1% and 37.2% of cases, respectively.Conclusions: Since, there are few relevant studies in our country, recent studies on infectious diseases could be used for national planning and medical requirements’ preparation, it seems that periodical assessments of these diseases are mandatory.