© 2014 Elsevier Inc. All rights reserved. Rett's syndrome (RTT) is an X-linked dominant neurodevelopmental disorder affecting females predominantly and is associated with mutations in the methyl-CpG-binding protein 2 gene. Diagnosis is based on strict clinical criteria with both classic (86%) and atypical (14%) forms recognized. The disorder follows a typical clinical profile of early normal development, regression of acquired speech and fine motor skills, followed by stabilization and improvement in interaction and communication with a slow but gradual progression of motor deficits. Survival is prolonged, the average age being slightly more than 50 years. Associated abnormalities include small stature, gastrointestinal dysfunction, seizures, breathing and sleep abnormalities, and scoliosis. Treatment is currently based on physical, occupational, and speech therapies, as well as management of intercurrent problems and nutritional support. Research into appropriate definitive treatment is on-going.