Paediatric patients hospitalised with varicella (n = 1575) were reported to a French national network between March 2003 and July 2005. Superinfection was identified in 50.3% of cases, principally of skin and soft-tissue (36.5%). The risk of superinfection increased with fever relapse, use of non-steroidal anti-inflammatory drugs, prolonged fever, an age of 1-5 years, and contamination at the childminder's home. Neurological complications were observed in 7.8% of cases, while pulmonary complications were less frequent (3.1%). Forty-nine patients had sequelae and eight patients died. Surveillance should continue in France with a view to the future implementation of a universal vaccination programme.