Abstract: The discovery of circulating fetal DNA in maternal blood has been an encouraging step forward in the prenatal diagnostic field. It has opened up the possibility of development of a noninvasive method for the genetic analysis of the fetus. Many techniques have been applied to the study of this fetal DNA, but automated sequencing has been seldom used. The intention of this study was to use the automated sequencing technique for the detection of a paternally inherited fetal mutation in maternal plasma. Maternal plasma samples from a pregnant woman, whose husband had a mutation (Q134X) in the RP2 gene, which is located in the X-chromosome, were collected at two different gestational ages (10th and 19th week of gestation) in order to determine whether the paternally inherited fetal mutation could be detected by automated sequencing. Restriction analysis was also performed to confirm the results. The fetal mutation was clearly detected in the maternal plasma by the use of automated sequencing. The automated sequencing enables the possibility of analyzing fetal sequences, at a nucleotide level, in order to detect mutations or polymorphisms which are distinguishable from maternal sequences.