Varicella-zoster virus (VZV) pneumonia is one of the most serious complications of this infection in adults. The objective of this study was to analyze the epidemiological and clinical characteristics in a large sample of patients with VZV pneumonia. This was a 10-y retrospective, descriptive, observational study. We studied 46 patients with VZV pneumonia, 21 men and 25 women, with a mean age 36 +/-11 y. A contact with an index case was observed in 57%, 76 were active smokers, 6.5% consumed drugs and 2 women were pregnant. The symptoms were: fever (83%), cough (83%), dyspnoea (63%), pleuritic pain (70%), and haemoptysis (6%) and started 3-5 days after the onset of blisters, except in 11% in whom respiratory symptoms appeared first. Arterial blood gases showed a mean PO(2)/FiO(2) of 308 +/-101 and 30 patients had a PO(2) of <55 mmHg--11 of these (4%) were admitted to the ICU, 8 required mechanical ventilation. Comparison of patients in the ICU with those on the general ward showed differences in the duration of fever (6.1 +/- 4.2 vs 3.2 +/- 1.1 days, p <0.001), mean stay (16.8+/-9.3 vs 7.2+/-2.4 days, p <0.001) and complications such as acute renal failure (p = 0.01) and acute respiratory failure (p < 0.001). Despite the severity of disease, no patient died. Once diagnosed, 98% were treated with acyclovir, combined with steroids in 6 and with antibiotics in 3 complicated with bacterial pneumonia. The prevalence for the period was 0.33 cases/100,000 inhabitants/y. In conclusion, VZV pneumonia has a severe course and accounts for a high percentage of admissions to the intensive care unit. The absence of mortality may be related to early treatment with acyclovir. Smoking was a risk factor for VZV pneumonia.