Rett syndrome (RTT) is a severe X-linked dominant neurodevelopmental disorder. Mutations in the MECP2 gene on chromosome Xq28 have been shown to be the cause of RTT. Using DNA samples from a RTT patient and her parents, we sequenced three exons and flanking intron regions of the MECP2 gene using the polymerase chain reaction. Sequencing of the MECP2 gene in the proband revealed a novel 41-base pair deletion in exon 4 (c.1152_1192del41). This mutation resulted in premature termination of the 487 amino acid protein at the 390th codon, predicting a partial loss of the C-terminal domain. We did not observe this mutation in either parent of the RTT patient, but further studies are needed to evaluate the possibility of germline mosaicism.