Rett syndrome (RS) is an incurable neurological disorder that occurs in females. Although the biological basis is unknown, there is substantial evidence suggesting a genetic basis. RS is characterized by an initial period of apparently normal psychomotor development followed by loss of communication skills and purposeful hand movement. Then, hand stereotypies, gait dyspraxia, and deceleration of head growth become apparent. Other problems include growth failure and epilepsy. There is no biological marker for RS; the diagnosis is based on well-delineated clinical criteria. The prevalence of RS is 1:23,000 live female births. Survival to 30-40 years or beyond is the rule rather than the exception. Treatment is both palliative and supportive. A vigorous approach to all aspects of care, including educational, medical, and psychosocial issues, is recommended.