Five girls, aged 2.5 years to 10 years, with Rett Syndrome are presented. The girls (four Chinese and one Indian) demonstrate the classic features of developmental regression with dementia, loss of hand function and stereotyped hand movements. There are as yet no pathognomonic laboratory markers and diagnosis can be difficult especially in the early stages before evolution of the full clinical spectrum. Adherence to current diagnostic criteria is essential. Rett Syndrome is probably not an uncommon cause of severe progressive neurological disability in girls.