ABSTRACT. Mutations in the myostatin (MSTN) gene can inactivate its expression and result in a non-functional protein, which leads to dramatic muscularity and a "double-muscling" phenomenon in many species. Using gene sequencing and polymerase chain reaction-singlestrand conformation polymorphism methods, polymorphisms of the MSTN gene were investigated as a candidate marker for growth in 288 goats. The results showed 2 novel single nucleotide polymorphisms: DQ167575 g.197G>A and 345A>T. Three potential genotypes (AA, AB, and BB) of substitution 197G>A in the 5'-untranslated region were detected in the 2 breeds. The polymorphism (CC and CD) of substitution 345A>T in exon I was segregated. The genetic diversity analysis revealed that Boer goat and Anhui white goat possessed intermediate genetic diversity in the P1 and P3 loci. Significant associations between the genotypes of the P3 locus and body weight, body length, and body height were observed in Boer goat and Anhui white goat (P < 0.05). It could be inferred that the MSTN gene may be a major gene or linked to the major gene affecting the goat growth traits. The polymorphic site could be a molecular marker-assisted selection program for body weight.