BACKGROUND: Rett syndrome is an X-linked dominant neurodevelopmental disorder affecting 1 from 10,000 to 15,000 females worldwide. The responsible gene, encoding methyl-CpG binding protein 2 was recently identified. Methyl-CpG binding protein 2 is thought to act as a global transcriptional repressor. In the methyl-CpG binding protein 2 gene are known 5 prevalent mutations that cause Rett syndrome. Four of them are detectable by restriction analysis. In this study we present the results of the molecular study of four prevalent mutations in the gene for methyl-CpG binding protein 2 in Czech and Slovak patients with Rett syndrome. METHODS AND RESULTS: 22 females with Rett syndrome were investigated by methods of molecular biology. Restriction analysis and direct sequencing of PCR products revealed in methyl-CpG binding protein 2 gene 3 different mutations (T158M, R168X, R270X) in six unrelated patients with Rett syndrome. Mutation R306C, frequent in Great Britain and Sweden, was not detected in our group of patients with Rett syndrome. CONCLUSIONS: The diagnosis of Rett syndrome and genetic counselling in affected families should go out from the close cooperation of the pediatric, neurologic, and genetic departments with the specialized laboratories dealing with the molecular biological diagnosis.