Background: Varicella pneumonia that results in respiratory failure or progresses to the institution of mechanical ventilation carries a significant morbidity and mortality despite intensive respiratory support and antiviral therapy, There has been no reported study of the role of corticosteroids in life-threatening varicella pneumonia, Design and methods: This was an uncontrolled retrospective and prospective study of all adult patients with a diagnosis of varicella pneumonia who were admitted to the ICUs of the Johannesburg group of academic hospitals in South Africa between 1980 and 1996, Patient demographies, clinical and laboratory features, necessity for mechanical ventilation, and complications were reviewed. The outcome and therapy off varicella pneumonia was evaluated with particular reference to the use of corticosteroids, Patients with comorbid disease and those already taking immunosuppressive agents were excluded, Key endpoints included length of ICU and hospital stay and mortality. Measurements and results: Fifteen adult patients were evaluated, six of whom received corticosteroids ire addition to antiviral and supportive therapy, These six patients demonstrated a clinically significant therapeutic response. They had significantly shorter hospital (median difference, 10 days; p<0.006) and ICU (median difference, 8 days; p=0.008) stays and there was no mortality, despite the fact that they were admitted to the ICU with significantly Bower median ratios between PaO2 and fraction of inspired oxygen than those patients (n=9) who did not receive corticosteroid therapy (86.5 vs 129.5; p=0.045). Conclusion: When used in addition to appropriate supportive care and early institution of antiviral therapy, corticosteroids appear to be of value in die treatment of previously well patients with life-threatening varicella pneumonia. The observations presented in this study are important and should form the basis for a randomized controlled trial, as no other relevant studies or guidelines are available.