Human cathelicidin (hCAP 18) is one of the main immunomodulators in the local immune response to Mycobacterium tuberculosis. There has been no information regarding the role of hCAP 18+ in the in vivo production of cytokine in childhood pulmonary tuberculosis (TB). We aimed to determine the intracellular cytokine secretion, including hCAP 18+ from monocytes and neutrophils of pulmonary TB in children, compared with healthy children. Fifteen patients with pulmonary TB were enrolled in the study as the study group, and 15 healthy children as the control group, between the age of 1 and 16 years. The patients' 25 hydroxyvitamin D levels were measured. The expression of hCAP 18+, TNF , INF- and IL-8 from CD14+ monocytes and CD15 + neutrophils was analyzed using the flow cytometry method. The statistical analysis was performed with PASW Statistics v.13.0. The mean vitamin D level was similar in both groups (P = 0.78). The expression of hCAP 18+ (P = 0.0001) and IL-8 from CD14 + (P = 0.0001) monocytes were significantly higher in the study group compared with the control group. There was no difference in the hCAP 18+ and IL-8 expression in CD 15+ neutrophils in both groups. The expression of TNF , INF- from CD14+ monocytes and CD 15+ neutrophils, in both study and control groups revealed no statistical differences. The level of hCAP 18+ and IL-8 released from monocytes were enhanced in the serum in childhood pulmonary TB. The present study is the first report detecting the intracellular hCAP 18+ expression in vivo in childhood pulmonary TB.