Fibrodysplasia ossificans progressiva (FOP) is a rare congenital disease with autosomal dominant transmission characterized by the presence of malformations of the big toes and of postnatal progressive heterotopic endochondral osteogenesis. We report the case of 3-year-old girl with dysplasia of the first metatarsal bones and progressive heterotopic ossificans of the right thigh due to previous diphtheria-tetanus-pertussis immunizations and several inappropriate surgical interventions. Direct sequence analysis identified a 617G-A nucleotide mutation in the patient but not in her parents or brother. Pedigree analysis suggests that a de novo mutation in the ACVR1 gene is responsible for the disease in this family. This is the first report of the results of a mutation analysis in a sporadic case of FOP in a Taiwanese patient.