Varicella rarely occurs in the adult but can cause multi-organ complications. The most frequent (15 to 30% involve varicella pneumonia of unpredictable outcome. In the healthy adult, outcome can be favourable in 5 days or inversely lead to respiratory distress and death in 10 to 20% of the cases. An analysis of the published cases does not reveal any factor predicting unfavourable outcome. A register of varicella pneumonia would help identify potential predictive factors.