OBJECTIVES: To demonstrate the clinical importance of adult chickenpox in terms of morbidity, mortality, and impact on hospital services, in Al Ain, United Arab Emirates. METHODS: A review was conducted of 607 consecutive hospitalized cases of adult chickenpox (1985-1996, Al Ain Hospital) for clinical findings and risk of developing varicella pneumonia. RESULTS: Leading clinical features were fever (98.9%), myalgia (26.9%), cough (24.6%), headache (15.4%), pharyngitis (14.7%), and profuse rash (12.2%). There were 26 cases of varicella pneumonia, of whom three died with respiratory failure (hospital case fatality 0.5%). Multivariate analysis (odds ratios in parenthesis) showed that cough (12.1), profuse rash (4.5), fever for more than 1 week (3.9), and age over 34 years (2.3) were the most significant predictors of pneumonia. CONCLUSIONS: Early aggressive therapy with intravenous acyclovir is recommended in patients at risk of pneumonia. In the community setting, there is a large proportion of adult immigrants (especially from South Asia) who are seronegative and at risk of complications and hospitalization. It is recommended that the varicella vaccine be offered to new immigrants after screening, to benefit themselves and the nonexposed community, and to reduce the economic burden of chickenpox on the health services and employers.