Congenital factor XIII (FXIII) deficiency is a rare autosomal recessive bleeding disorder mainly caused by mutations in the F13A1 gene on 6p25.1, which lead to defective A subunit of FXIII. We herein describe two unrelated Korean patients with congenital FXIII deficiency. Proband 1 (a 30-year-old man) and Proband 2 (a 10-year-old girl) presented with severe bleeding episodes (huge intramuscular hematoma and acute intracerebral hemorrhage). Coagulation screening tests for bleeding diathesis were normal, but the FXIII activity was undetectable on urea clot lysis assay. The molecular genetic analysis of F13A1 revealed two mutations in the patients: Proband 1 was homozygous for a previously reported mutation c.1984C>T (p.Arg662) and Proband 2 was compound heterozygous for c.1029T>A (p.His343Gln) and c.1984C>T (p.Arg662). His343Gln was a novel missense mutation occurring in the core domain of the FXIII A subunit. This is the first report of genetically confirmed FXIII deficiency in Korea, with novel and recurrent F13A1 mutations.