Abstract： Objective To analyze the effect of minimally invasive surgery on patients with upper ureteral calculi in lateral position and the effect of intraoperative use of low dose dexamethasone on serum levels of C-reactive protein and procalcitonin.Methods Clinical data of 261 patients with upper ureteral calculi treated by lateral position minimally invasive surgery from January 2016 to January 2018 in Xiaolan People's Hospital of Zhongshan were retrospectively analyzed.The patients were divided into three groups:ureteroscope pneumatic lithotripsy group(PL group,123 cases),ureteroscope holmium laser lithotripsy group(LL group,95 cases) and PL combined with percutaneous nephroscope lithotripsy (PCNL) group (43 cases).Dexamethasone 5 mg was used in all patients during surgery.Surgical effect and postoperative levels of serum C-reactive protein and procalcitonin were analyzed.Results Success rate of lithotripsy,calculi-removal rate,complication rate,decrease of hemoglobin level were significantly higher,operation time and postoperative hospital stay time were significantly longer in PL combined with PCNL group than those in PL group and LL group[100.0％ (43/43) vs 94.3％ (116/123),98.9％ (94/95);100.0％ (43/43) v s 93.5 ％ (115/123),96.8％ (92/95);9.3 ％ (4/43) vs 3.3 ％ (4/123),3.2％(3/95);(12.9±5.4)g/L vs (5.8±2.2),(6.2 ±3.4)g/L;(48 ±8)min vs (40 ±9),(42 ±8)min;(8.6 ± 1.6) d vs (2.8 ± 0.6),(2.7 ± 1.0) d] (all P ＜ 0.05).Serum levels of C-reactive protein and procalciton significantly decreased after surgery and the levels in PL combined with PCNL group were significantly lower than those in PL group and LL group[(0.31 ±0.06) vs (0.40 ±0.07),(0.37 ±0.09);(0.32 ±0.05) vs (0.41 ± 0.08),(0.38 ±0.06)] (all P＜0.05).Conclusion Lateral position minimally invasive surgery has a good clinical effect on upper ureteral calculi and low dose of dexamethasone can effectively reduce serum levels of C-reactive protein and procalcitonin.