OBJECTIVE: To study the expression of serum Clara cell secretory protein 10 (CC10) and total IgE concentration in wheezing children under 5 years old. METHODS: Fifty-nine children with recurrent wheezing under 5 years old were classified into two groups: wheezing group 1 with atopic high risks (n=33) and wheezing group 2 without atopic high risks (n=26). Twenty-three children without infectious diseases served as a control group. Serum levels of CC10 and IgE were measured using a solid-phase sandwich ELISA. RESULTS: The serum levels of CC10 in wheezing group 1 (3.95±1.26 ng/mL) and wheezing group 2 (5.41±1.64 ng/mL) were significantly lower than those in the control group (8.72±2.23 ng/mL; P<0.01). The wheezing group 1 showed more decreased serum levels of CC10 compared with wheezing group 2 (P<0.05). The serum IgE levels in wheezing group 1 were significantly higher than those in wheezing group 2 and the control group (P<0.05). There were no significant differences in serum IgE levels between the wheezing group 2 and control group. There was a negative correlation between serum levels of CC10 and IgE in wheezing group 1 (r=-0.912, P﹤0.01). CONCLUSIONS: Serum CC10 levels decrease remarkably in wheezing children, and more significant decrease is noted in patients with atopic high risks. Serum CC10 levels are negatively correlated to serum IgE levels in patients with atopic high risks.