Background: Precocious puberty is known as an idiopathic, sporadic disease. Recently, specific mutations have been shown to cause familial central precocious puberty (CPP). The Makorin ring finger 3 (MKRN3) gene plays a key role in puberty; loss-of-function mutations in the gene trigger familial CPP. To date, most described patients have been Western; few Asians with CPP have been documented. Objective: To identify MKRN3 gene mutations or polymorphisms in Korean patients with familial CPP. Method: We recruited 26 patients with CPP and their parents (13 families). We measured endocrine and auxological parameters, and sequenced all MKRN3 exons. Results: We found no MKRN3 mutations. Two MKRN3 exon polymorphisms were identified. The g.23566445 C/T polymorphism was found in 8 families; a novel single nucleotide polymorphism (SNP) g.23567001 A/C was found in 1 family. These variants are synonymous SNPs; their functional roles remain unknown. Conclusion: MKRN3 mutation is uncommon in Korean patients with familial CPP. Ethnic variation in MKRN3 mutational status is thus evident.