Noonan syndrome (NS) is an autosomal dominant disorder presenting with characteristic facies, short stature, skeletal anomalies, and congenital heart defects. Mutations in protein-tyrosine phosphatase, nonreceptor-type 11 (PTPN11), encoding SHP-2, account for 33-50% of NS. This study screened for mutations in the PTPN11 gene in 34 Taiwanese patients with NS. Mutation analysis of the 15 coding exons and exon/intron boundaries was performed by polymerase chain reaction and direct sequencing of the PTPN11 gene. We identified 10 different missense mutations in 13 (38%) patients, including a novel missense mutation (855T>G, F285L). These mutations were clustered in exon 3 (n = 6) encoding the N-SH2 domain, exon 4 (n = 2) encoding the C-SH2 domain, and in exons 8 (n = 2) and 13 (n = 3) encoding the PTP domain. In conclusion, this study provides further support that PTPN11 mutations are responsible for Noonan syndrome in Taiwanese patients.