Severe congenital neutropenia is a rare hematological disease characterized by a selective decrease in circulating neutrophils, maturation arrest of granulocytic precursors at the promyelocyte stage, and recurrence of infections. A 2-month-old male infant (patient A) and a 14-month-old female child (patient B) were referred to our hospital due to severe neutropenia. Sequencing analysis of ELA2 and HAX1 genes was performed. Two single nucleotide polymorphisms of HAX1 gene were found. They were 5,104T-->G point mutation of exon 1 and 5,474A-->G point mutation of intron 1 in HAX1 gene. The mutation of ELA2 gene was not found. The patient A showed a good response to granulocyte colony-stimulating factor (G-CSF) treatment and the absolute neutrophil count recovered to 1,195/microL. But the patient B showed a partial response to G-CSF treatment and experienced several episodes of herpetic gingivostomatitis, oral ulcer, acute pharyngotonsillitis and otitis media during follow-up.