Abstract Background Aromatase excess syndrome (AEXS) is a rare autosomal dominant disorder caused by CYP19A1 overexpression. Clinical manifestations of AEXS include pre- or peri-pubertal gynecomastia, advanced bone age and compromised adult height. Case presentation Here we report an 8-year-old boy diagnosed with AEXS by chromosomal array that revealed a 1.1 Mb novel de novo duplication at 15q21.2, with a predicted final height of 157.4 cm. We prescribed letrozole and growth hormone (GH) to maximize his linear growth. Without further bone age advancement, his height increased from 137.7 cm to 144 cm after an 8-month treatment period. Conclusions We identified a novel duplication at 15q21.2 in AEXS, and found that aromatase inhibitor (AI) plus GH might provide a better growth-promoting approach for AEXS patients.