Pfeiffer syndrome (PS) is mainly characterized by craniosysnostosis, midface hypoplasia, great toes with partial syndactyly of the digits, broad and medially deviated thumbs. It is caused by allelic mutations in the fibroblast growth factor receptor 1 and 2 (FGFR1 and 2) genes. This study describes the clinical and genetic features of five Brazilian families affected by PS. All patients exhibited the classical phenotypes related to PS. The genetic analysis was able to detect the mutations Cys278Phe, Cys342Arg, and Val359Leu in three of these families. Two mutations were de novo, with one familial. We identified pathogenic mutations in four PS cases in five Brazilian families by PCR sequencing of FGFR1 exon 5 and FGFR2 exons 5, 8, 10, 11, 15, and 16. The clinical and genetic aspects of these families confirm that this syndrome can be clinically variable, with different mutations in the FGFR2 responsible for PS.