Objective To investigate the protective role of ulinastatin combined with verapamil in rat acute lung ischemia reperfusion injury (ALIRI).Methods Rat ALIRI models were established and randomly divided into 4 groups:control group,ulinastatin pretreatment group,verapamil pretreatment group,and ulinastatin + verapamil pretreatment group.The dry weight (W/D) ratio,the content of lung tissue malondialdehyde (MDA) and nitric oxide (NO),the activity of myeloperoxidase (MPO) and super-oxide dismutase (SOD) and lung tissue morphological changes were measured 4 h after reperfusion.Results 4 h after reperfusion,W/D ratio in ulinastatin + verapamil pretreatment group was (4.78 ±0.49),significantly lower than in control group (7.05 ± 0.74,t =5.904,P ＜ 0.01),also significantly lower than in ulinastatin pretreatment group (6.16 ± 0.62,t =2.387,P ＜ 0.05) and verapamil pretreatment group (5.91 ±0.47,t =2.176,P ＜ 0.05).MDA content in ulinastatin + verapamil pretreatment group was (1.34 ±0.10) nmol/mg protein,significantly lower than in control group [(2.08 ± 0.15) nmol/mg protein,t =6.324,P ＜0.01],also significantly lower than in ulinastatin pretreatment group [(1.83 ±0.11) nmol/mg protein,t =2.692,P ＜ 0.05] and verapamil pretreatment group [(1.76 ± 0.17) nmol/mg protein,t =3.008,P ＜0.05).NO content in ulinastatin + verapamil pretreatment group was (0.71 ± 0.16) μmol/L,significantly higher than in control group [(0.43 ±0.12) μmol/L,t =6.168,P ＜ 0.01],also significantly higher than in ulinastatin pretreatment group [(0.57 ± 0.14) μmol/L,t =3.637,P ＜ 0.05] and verapamil pretreat-ment group [(0.60 ±0.17) μmol/L,t =3.243,P ＜0.05].MPO activity in ulinastatin + verapamil pretreat-ment group was (0.72 ± 0.05) U/g,significantly lower than in control group [(1.03 ± 0.09) U/g,t =5.210,P ＜ 0.01],also significantly lower than in ulinastatin pretreatment group [(0.84 ± 0.07) U/g,t =2.315,P ＜0.05] and verapamil pretreatment group [(0.86 ±0.10) U/g,t =2.306,P ＜0.05].SOD activi-ty in ulinastatin + verapamil pretreatment group was (51.66 ± 3.97) U/mg protein,significantly higher than in control group [(30.19 ±3.69) U/mg protein,t =5.731,P＜0.01],also significantly higher than in uli-nastatin pretreatment group [(42.07 ± 4.24) U/mg protein,t =3.134,P ＜ 0.05] and verapamil pretreatment group [(43.12 ± 4.88) U/mg protein,t =3.043,P ＜ 0.05].Histopathologic score of the lung tissue in ulinastatin + verapamil pretreatment group was (2.9 ± 1.8),significantly lower than in control group (8.6 ±3.5,t =7.308,P ＜ 0.01),also significantly lower than in ulinastatin pretreatment group (5.2 ± 2.7,t =1.927,P ＜0.05) and verapamil pretreatment group (5.4 ±2.8,t =2.l13,P ＜0.05).Conclusion Ulinas-tatin combined with verapamil can significantly reduce the lung ischemia-reperfusion injury,and the effect is better than ulinastatin or verapamil used alone.