The objective of this study was to determine the value of an e-mail listserv for parents of children with Rett syndrome, a rare neurologic disorder. This Web-based survey was completed by parents and carers. The setting was an e-mail listserv established by the International Rett Syndrome Association for parents of children with Rett syndrome and other interested persons. The participants included members of the e-mail listserv Rettnet. The main outcome measures were the perceived advantages and disadvantages of the listserv, overall rating of usefulness, and reasons for satisfaction or dissatisfaction. Most (81.5%) of the participants felt that Rettnet provided helpful advice concerning their child's management. They also indicated that Rettnet was useful in dealing with their child's education and as a source of carer support. They rated it highly (mean 8.1 on a scale of 1 to 10), and the most common reason given for recommending the service to other parents was the emotional support provided. E-mail listservs can play an important role in disseminating information and providing networking and support to parents of children with rare disorders. Their impact and influence warrant attention from health professionals, including neurologists.