PurposeRecombinant human cytoglobin (rhCygb) has been demonstrated to anti-inflammation, anti-oxidation, anti-fibrosis in liver and kidney in animal disease models. However, the effect of rhCygb on the progression of pulmonary fibrosis is still unclear. The aim of this study was to investigate the therapeutic effect of rhCygb in the bleomycin (BLM)-induced pulmonary fibrosis rats.MethodsWe tested whether rhCygb would reverse lung fibrosis (at day 28 and 56) in Sprague-Dawley rats treated with bleomycin. Bleomycin (5mg/kg) resulted in fibrosis by CT and serum measurement at day 7. Effects of rhCygb treatment on morphological and CT imaging of the lung, as well as serial serum levels of biomarkers with progressive lung fibrosis were tested at day 28 and 56.ResultsIn BLM-treated rats (7 days), the well-established lung fibrosis was evidence by changes in rat lungs with CT images and serum levels of hyaluronic acid (HA), laminin (LN), procollagen III N-terminal peptide (PIIINP) and type IV collagen (IVC).After treatment with rhCygb for 49 days, we found significantly decreasing in HA, LN, PIIINP and IVC levels almost to controls. Hydroxyproline (HYP) , CT mean lung density（MLD）and Masson collage volume fraction (CVF) were also significantly reduced. Furthermore, CT MLD positively correlated with serum levels of HA, LN, PIIINP, IVC, and HYP, and especially with CVF.ConclusionrhCygb may be a new potential medicine for reversing lung fibrosis in the future.