Background Periostin is a matricellular protein, and its synthesis in airway epithelial cells and lung fibroblasts is induced by interleukin (IL)‐4 and IL‐13. The significance of periostin as a biomarker of TH2‐induced airway inflammation, and (importantly) as a measure of the response to TH2‐targeted therapy, has recently been emphasized. We explored the relationship between periostin and airway hyperresponsiveness (AHR) in asthmatic children. Methods The study included 83 children aged 6–15 years in an asthmatic group (n = 54) and healthy controls (n = 29). We measured the periostin levels in serum and performed methacholine and mannitol provocation challenges. The responses to mannitol were expressed as the provocative dose causing a 15% fall in the FEV1 (the PD15 dose). Results Of the 54 subjects with asthma, all had positive methacholine bronchial provocation test (BPT) results and 38 had positive mannitol BPT results. Children with asthma had significantly higher periostin levels than controls 76.0 (65.0–91.8) vs 71.0 (57.5–80.0) ng/mL; P = 0.017. Periostin levels were significantly correlated with both the methacholine PC20 and mannitol PD15 values. Conclusion Serum levels of periostin, a new biomarker induced by IL‐13, were higher in asthmatic children, and were associated with AHR to methacholine and mannitol.