The WHO 2008 definition of chronic neutrophilic leukemia (CNL) is based on clinical and laboratory parameters but not on molecular abnormalities. Mutations in CSF3R, SETBP1 and CALR are reported in patients with chronic neutrophilic leukemia (CNL). However, because CNL is rare, there are few large studies of this issue. We sequenced these genes in 14 patients who met the WHO-criteria of CNL. 8 subjects had CSF3R(T618I), 6 SETBP1 mutations and 1 a CALR mutation. Our data suggest mutation analysis of CSF3R, SETBP1 and CALR should be included in the diagnostic criteria for CNL. These data may also have therapy implications.