Pneumonia is a common cause of hospitalization and is associated with high morbidity in children. Tumor necrosis factor-alpha (TNF-alpha) and Interleukin-6 (IL-6) are primary mediators of inflammation, and have been implicated in a large number of infectious and non-infectious inflammatory diseases. The serum concentrations of TNF-alpha and IL-6 were measured by enzyme-linked immunosorbent assay (ELISA) in 27 patients with bacterial pneumonia (n = 12) or respiratory syncytial virus (RSV) pneumonia (n = 15) and in 15 healthy control subjects. TNF-alpha concentrations of patients with bacterial pneumonia in acute stage (16.94 +/- 5.70 ng/L) were significantly higher than those in convalescent stage (5.80 +/- 0.75 ng/L), in patients with RSV pneumonia (5.06 +/- 0.44 ng/L) and in healthy control subjects (5.39 +/- 0.68 ng/L) (p < 0.005). TNF-alpha concentrations of patients with RSV pneumonia were not significantly different from those of the control group. IL-6 concentrations of patients with bacterial pneumonia in acute stage (465.94 +/- 290.30 ng/L) were significantly higher than those in convalescent stage (22.04 +/- 15.08 ng/L), in patients with RSV pneumonia (7.65 +/- 2.58 ng/L), and in healthy control subjects (0.84 +/- 0.08 ng/L) (p < 0.0005). There was significant difference between patients with RSV pneumonia and the healthy control group (p < 0.005). In summary, there were significant differences in TNF-alpha and IL-6 concentrations between acute stage and convalescent stage in patients with bacterial pneumonia, making them useful as markers for bacterial pneumonia. Further studies are needed to establish the potential diagnostic and prognostic value of TNF-alpha and IL-6.