Congenital insensitivity to pain with anhidrosis (hereditary sensory and autonomic neuropathy type IV) is a rare autosomal recessive disorder caused by a defect in neurotrophic tyrosine kinase receptor and nerve growth factor, as reported in previous studies. This report is of a 6-month-old male infant with typical symptoms and signs of congenital insensitivity to pain with anhidrosis. He had a homozygous insertion mutation with c.2086_2087 ins C of neurotrophic tyrosine kinase receptor type 1 (NTRK1) gene with both parents as heterozygous carriers. This mutation may have a strong relation to hereditary sensory and autonomic neuropathy type IV Taiwanese patients. This is the youngest reported patient in Taiwan and first reported with congenital insensitivity to pain with mutation of NTRK1 gene inherited from the parents. Early diagnosis may provide appropriate medical care and education for these children and their families for better prognosis.