Objective To investigate the clinical efficacy and safety of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) in treatment of children with Alport syndrome (AS).Methods A total of 22 children with AS in Department of Pediatrics,Guangzhou First People's Hospital and Department of Pediatrics,Shenzhen People's Hospital between January 2013 and December 2017 were selected.But four children were not included in this study since they did not take medication regularly,and the other 18 cases were included in this study.All the 18 children were initially treated with ACEI.The observation time was from 1 to 5 years.If the symptoms were not effectively controlled,treatment plan would be changed to ACEI combined with ARB treatment.The observation time was from 1 to 3 years.The clinical data and laboratory examination results [including 24-hour urine protein (mg/24 h),urine red blood cell count,plasma albumin (Alb),urea nitrogen (BUN),serum creatinine (Scr),total cholesterol (TC)] were collected for retrospective analysis.Results Eighteen patients started their treatment with ACEI inhibitors (Fosinopril).Within 2 years of treatment,the urinary protein and urinary red blood cells in the children decreased to 47.7％ and 41.3％,respectively,and the differences were all statistically significant (all P ＜ 0.05),and the renal function was stable within the normal range.Two years later,7 patients had elevation of urinary protein and urinary erythrocyte elevations and decrease of renal function,and they were treated with ACEI and ARB (Losartan).The other children had no significant change in urine protein and urine red blood cells in the 3 rd,4th,and 5th year,and their renal function was stable.After ACEI treatment alone for 5 years,urinary protein was 47.8％ lower than before treatment,and the difference was statistically significant (P ＜ 0.05);urinary red blood cells decreased to 32.0％ compared with before treatment,and the difference was statistically significant (P ＜ 0.05).Seven patients with ACEI alone had poor efficacy,after the treatment with ACEI combined with ARB,the urinary protein and urine red blood cells were lower in the first year and the renal function improved.There was no significant change in urinary protein and urine red blood cells in the 2nd and 3rd year,and renal function was stable.After ACEI combined with ARB treatment for 3 years,urinary protein decreased to 42.3％ before treatment,and the difference was statistically significant (P ＜ 0.05),and urinary red blood cells decreased to 46.9％ compared with before treatment,and the difference was statistically significant(P ＜ 0.05).Conclusions ACEI treatment of children with AS can reduce urine protein and help delay renal failure.For children with poor efficacy of ACEI treatment,ACEI combined with ARB may have a certain effect.ARB can be used as an adjunctive treatment for patients with AS who have a poor response to ACEI alone.