Objectives : Idiopathic pulmonary fibrosis (IPF) is chronic fibrotic interstitial pneumonia and the pathogenesis is unknown. Peucedani Radix is well-known for the treatment of respiratory diseases and pulmonary hypertension. This study was to evaluate the effectiveness of Peucedani Radix on the bleomycin-induced lung fibrosis model (BLFM) in mouse. Methods : We induced lung fibrosis by intratracheal instillation of bleomycin in C57BL/6J. We compared two groups BLFM without Peucedani Radix (group I) and BLFM with Peucedani Radix (group II). We performed bronchoalveolar lavages (BAL) and obtained lung specimens from both group I and II on the 7th (A) and 21st (B) day, and also for the normal group. We compared with group I and II to find BAL by using ANOVA test and to find pathologic symptoms by using semiquantitative histological index (SHI). Results : In BAL, total cell counts, lymphocytes, and neutrophils was increased in both group I and II comparing with normal group. However, lymphocyte level was decreased more in group IIB than group IB. It was statistically significant. In microscopic findings, scores of SHI in normal group, group IB and IIB were 0.33, 4.47, and 1.96 each. Conclusions : Peucedani Radix might have inhibitory effect on lung fibrosis by reducing inflammatory cells in bleomycin-induced lung fibrosis model in mouse.