OBJECTIVE To define the rate of complications of adult varicella, including pneumonia, and to determine the association of such complications with pregnancy. METHODS Retrospective, descriptive case series of consecutive adult emergency department patients with primary varicella seen over a 31-month period in an urban county hospital. RESULTS A total of 130 patients were identified, with a mean age of 23.9 +/- 6.1 years; 69 (53%) were female. Thirteen patients (10.0%) had pneumonia; 6 of these were hospitalized. Two patients admitted with pneumonia had significant underlying comorbid disease and expired from respiratory failure. The remaining 4 admitted patients recovered uneventfully. Four of the 7 patients discharged with pneumonia were known to have recovered uneventfully. Twenty-eight (41%) of the 69 female study patients were pregnant; 7 of these (25%) were admitted, with admission diagnoses of pneumonia (1), active labor (2), and pregnancy with varicella (4). Incidence of pneumonia in pregnant patients was 3.6% (1 of 28; 95% confidence interval, 1% to 18.3%). All 7 admitted pregnant patients and the 19 (of 21) discharged pregnant patients who were contacted recovered uneventfully. No congenital anomalies or perinatal complications were noted in the infants of the 26 mothers with documented follow-up. CONCLUSIONS Hospital admission should be considered for adults with varicella pneumonia, especially if they have significant comorbid disease. It does not appear that pregnant women are at increased risk of developing varicella pneumonia.