Abstract: Objective: The objective of this study was to determine Growth Hormone (GH) gene polymorphisms and their association with productive traits, including body weight, at ages 1, 2, 3, 4, 5, 6, 7 and 8 weeks. Methodology: Polymorphisms in exon 1 of the GH gene were evaluated in two duck populations in West Sumatra Province Indonesia (Pitalah and Kumbang Janti ducks). For this purpose, blood samples were collected and DNA samples were extracted using the Promega Wizard® Genomic DNA Purification Kit. For this purpose, a total 225 ducks blood samples were collected from 145 male and 80 female ducks. Genetic polymorphisms were determined with the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method using the Eco721 restriction enzyme and agarose gel electrophoresis. Direct sequencing of some samples was used to confirm the results. Results: Two alleles (GHG and GHA) and three genotypes (GH/GG, GH/GA and GH/AA) were found in the studied duck samples at locus GH/Eco721. In both groups of ducks, the dominant allele was GHG. The most frequent genotype in the examined ducks was GH/GA. Three genotypes were observed in the Pitalah ducks, whereas two genotypes (GH/GA and GH/GG) were identified in the Kumbang Janti ducks and in the males. Pitalah ducks with the GH/GA genotype were characterized by a higher (p<0.01) body weight than the ducks with the GH/GG and GH/AA genotypes. This same trend was observed in the female Pitalah ducks; individuals with the GH/GA genotype had higher body weights (p<0.05 and p<0.01) than the birds with the two other detected genotypes. Kumbang Janti ducks with the GH/TT genotype were distinguished by higher values of all evaluated traits compared to the ducks with the GH/CT and GH/CC genotypes; however, most of the recorded differences were not significant. The only trait that was markedly impacted (p<0.05) by the polymorphism of GH gene intron 1 was the body weight at 5, 6, 7 and 8 weeks. Conclusion: This study found that the GH/TT genotype was associated with a higher body weight at 5, 6, 7 and 8 weeks of age in Pitalah and Kumbang Janti ducks.