Diagnosis should be based on laboratory evi-dence of the CFTR abnormality, including an elevated concentration of the sweat chloride, identification of two CFTR mutations, or evidence of the characteristic patterns of ion transport across the nasal epithelia(4). Sweat chloride levels between 60 and 165 mEq/L are considered diagnostic for CF.(5) However, not all of these investigative tools are available in Thailand, which may explain the lack of case reports from Thailand. The authors encountered three Northeast Thai infants with this rare disease and present the findings.