OBJECTIVE Angiotensin-converting enzyme 2 (ACE2) gene polymorphisms have been shown to be implicated in hypertension, diabetic nephropathy, and other diseases. However, it remains unclear whether ACE2 gene polymorphisms are involved in the development of primary nephrotic syndrome (PNS) in children. The aim of this study was to assess the association between A9570G polymorphisms of ACE2 gene and PNS in a group of Han children in Guangdong Province, China. METHODS The genotype distribution and allele frequency of ACE2 gene A9570G in 66 children with PNS and 60 healthy subjects (control group) were analyzed by polymerase chain reaction and restriction fragment length polymorphism. RESULTS Allele frequency and genotype distribution showed no significant difference between the PNS and control groups whether in female or in male children (P>0.05). The PNS group was classified into the glucocorticoid-sensitive and glucocorticoid-resistant subgroups according to glucocorticoid treatment response. Subgroup analysis revealed that in female children, the frequency of GG genotype was 17% in the glucocorticoid-sensitive group vs 45% in the glucocorticoid-sensitive group (P=0.018); the frequency of G allele was 31% in the glucocorticoid-sensitive group vs 61% in the glucocorticoid-resistant group (P=0.023). In male children, the frequency of G genotype/G allele was 36% in the glucocorticoid-sensitive group vs 64% in the glucocorticoid-resistant group (P=0.017). CONCLUSIONS There is no clear association between ACE2 gene A9570G polymorphisms and childhood PNS, but ACE2 gene A9570G polymorphisms might be associated with glucocorticoid treatment response in children with PNS. The G allele might be a genetic susceptibility factor of glucocorticoid resistance in children with PNS.