Objectives: This study was designed to evaluate the immune status of health care workers against varicella zoster in a university hospital in Teheran, Iran, and to compare the history of chickenpox infection with the presence of varicella antibodies in this population. Methods: Serologic testing for varicella was performed for 405 health care workers with different job categories and at different age. The enzyme immunoassay was used for determining IgG antibodies against varicella zoster virus Results: A total of 405 health care workers, aged 19-50 years (median: 29 years), were examined. Of these, 289 (71.4%) were found to be seropositive. No statistically significant differences were observed between gender, age, or occupation, and seropositivity (p = 0.09, 0.75, 0.54. respectively). Statistical analysis revealed that the correlation between chickenpox history and seropositivity showed a 62.3% sensitivity, 72.4% specificity, 84.9% positive predictive value, and 43.5% negative predictive value. Conclusions: Serologic screening of health care workers is essential to determine their immunity to varicella, regardless of the age, occupation and history of infection. This population is recommended to be considered a target group for future immunization programs in Iran. Varicella is a common childhood disease. Nearly a 100% seropositivity to VZV has been documented in children between 11-13 years of age in the USA. An epidemiological variation is being reported between the temperate and tropical climate countries, with varicella occuring mainly among young adults in the tropical regions [2]. Key words: Health care workers, Varicella zoster infection, ImmunizationThe general adult seroprevalence rates amount to 81.3% in the United Arab Emirates, 100% in Belgium, 96.6% in Israel, 95% in Turkey, 95.5% in Spain, 50% in Sri Lanka,.Moreover, nosocomial transmission of VZV is also reported in health care workers (HCWs) [10]. It seems that A checklist was completed including demographic data and the history of varicella. Individuals with acute varicella infection, those under immunosuppressive therapy, or those having blood transfusion during the year 2008, were excluded from the study. The local ethics committee approved the study protocol, and a signed informed consent was obtained from each participant. Blood samples were collected from each individual and the separated serum was stored at -20°C prior to testing. EIA for varicella-specific IgG was performed using commercial virus-specific IgG EIA kits (varicella IgG EIA well, RADIM, Italy; sensitivity 100%, specificity 88%). Optical density values were indexed according to the manufacturer's instructions. Sera were classified as negative if the OD was less than 0.20 and as positive if it was higher than 0.70; sera with OD between 0.20 and 0.70 were considered equivocal. Equivocal values were considered negative. Statistical analysis was performed using the SPSS 13 software. After conducting descriptive statistical analyses, we used the chi square test to study t...