Objective To explore the effect of early short-term use of low-dose steroids on early acute lung injury (EALI) after video-assisted thoracoscopic lobectomy. Methods Patients who underwent video-assisted thoracoscopic lobectomy in our department from January 2019 to January 2022 were selected for this retrospective cohort study. They were divided into an early steroid treatment group and a control group based on whether steroids were used in the early postoperative period. In the early steroid treatment group, in addition to routine postoperative treatment, low-dose methylprednisolone was administered intravenously, at 80-120 mg/d for 3 consecutive days. In the control group, routine postoperative treatment was given, but no steroids were used in the first 3 days. A chest computed tomography (CT) scan was performed on postoperative day (POD) 1, and POD3 or POD4 to assess lung injury. Chest CT scores, the EALI incidence, the length of hospital stay, and the incidence of poor incision healing were recorded. ResultsA total of 521 patients were included, consisting of 255 males and 266 females, aged 11-80 years. There were 318 patients in the early steroid treatment group and 203 patients in the control group. On POD1, the incidence of EALI was 16.0% in the control group and 13.8% in the steroid group, with no significant difference between the two groups (P>0.05). There was also no significant difference in the CT scores of patients with EALI in the two groups (P>0.05). On POD3/4, the incidence of EALI was 33.6% in the control group and 22.7% in the steroid group, showing a significant difference (P=0.007). When comparing the CT scores of patients with EALI in both groups, the scores were lower in the steroid group, but the difference was not significant (P>0.05). The overall incidence of EALI on POD1-4 was 37.4% in the control group and 26.1% in the steroid group, showing a significant difference (P=0.007). Of these, 28.9% of patients in the control group showed radiological progression, which means new EALI occurred or existing EALI progressed, while the progression rate was 14.8% in the steroid group (P<0.001). The length of hospital stay was significantly shorter in the steroid group compared to the control group (P<0.001), but the incidence of poor incision healing was not (P>0.05). Conclusion Early use of corticosteroids cannot reduce the incidence and severity of EALI on POD1, but it can reduce the incidence of EALI on POD3/4 and decrease the risk of radiological progression, and also lower the overall risk of EALI after surgery, without extended postoperative hospital stays or increased incidence of poor incision healing. Therefore, early postoperative use of low-dose corticosteroids can help to inhibit the occurrence and progression of EALI. It is suggested to use as early as possible especially in patients with high risks of postoperative EALI.