Rett syndrome is one of the most common causes of mental retardation in females. It is an X linked dominant inherited disorder characterized by regression of language and motor milestones, acquired microcephaly, severe mental retardation and loss of purposeful use of hands. Its hallmark is a repetitive “hand-washing” movement. In the majority of cases, defects on genes MECP2 and CDKL5 have been identified. On the following report we present our first experience involving Rett Syndrome patients, analyzing their main clinical and electroencephalographic features, progression of disease and its treatment. We also make an update of genetics and treatment options. We believe that this study will provide the necessary tools to make an early diagnosis in our environment, reach the most accurate treatment and the appropriate genetic counseling for the families.