This study measured use and cost of health sector and related services in Rett syndrome and effects of socio-demographic, clinical severity and genetic factors on costs. The study population consisted of individuals with Rett syndrome registered with the Australian Rett Syndrome Database in 2004. Descriptive analysis was used to examine patterns of resource use and costs, and logistic regression to analyse factors associated with higher costs. We found the use of health sector and related resources varied by type of resource. Mean annual cost per case was $21,158 (range $238-$85,776). High cost items included long-term residential care, therapy services out of school and paid home and community care. Factors associated with increasing odds of being above the median cost were clinical severity and the p.R255X mutation. Compared with the youngest cases, cases in the 5-14 year age group and the 15-24 year age group were at lower odds of being above the median cost. Needs relating to health sector and related resources can result in considerable costs for individuals with Rett syndrome. Many households caring for dependents with Rett syndrome are like to be facing undue financial pressures from the additional costs of disability. (Contains 6 tables and 1 figure.)